{"id":7808,"date":"2026-03-26T17:34:25","date_gmt":"2026-03-26T10:34:25","guid":{"rendered":"https:\/\/thecatalyst.edu.vn\/blogs\/?p=7808"},"modified":"2026-03-26T17:34:34","modified_gmt":"2026-03-26T10:34:34","slug":"once-in-a-blue-moon","status":"publish","type":"post","link":"https:\/\/thecatalyst.edu.vn\/blogs\/once-in-a-blue-moon","title":{"rendered":"Once In A Blue Moon l\u00e0 g\u00ec? Ngu\u1ed3n g\u1ed1c v\u00e0 c\u00e1ch d\u00f9ng chi ti\u1ebft"},"content":{"rendered":"<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_66_1 counter-hierarchy ez-toc-counter ez-toc-custom ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title \" >N\u1ed9i dung ch&iacute;nh<\/p>\n<span class=\"ez-toc-title-toggle\"><a href=\"#\" class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" aria-label=\"Toggle Table of Content\"><span class=\"ez-toc-js-icon-con\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #28282d;color:#28282d\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #28282d;color:#28282d\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/span><\/a><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/thecatalyst.edu.vn\/blogs\/once-in-a-blue-moon\/#I_Once_in_a_blue_moon_nghia_la_gi\" title=\"I. Once in a blue moon ngh\u0129a l\u00e0 g\u00ec?\">I. Once in a blue moon ngh\u0129a l\u00e0 g\u00ec?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/thecatalyst.edu.vn\/blogs\/once-in-a-blue-moon\/#II_Nguon_goc_cua_thanh_ngu_Once_in_a_blue_moon\" title=\"II. Ngu\u1ed3n g\u1ed1c c\u1ee7a th\u00e0nh ng\u1eef Once in a blue moon\">II. Ngu\u1ed3n g\u1ed1c c\u1ee7a th\u00e0nh ng\u1eef Once in a blue moon<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/thecatalyst.edu.vn\/blogs\/once-in-a-blue-moon\/#III_Cach_su_dung_Once_in_a_blue_moon_trong_cau\" title=\"III. C\u00e1ch s\u1eed d\u1ee5ng Once in a blue moon trong c\u00e2u\">III. C\u00e1ch s\u1eed d\u1ee5ng Once in a blue moon trong c\u00e2u<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/thecatalyst.edu.vn\/blogs\/once-in-a-blue-moon\/#IV_Nhung_cum_tu_lien_quan_va_trai_nghia_voi_Once_in_a_blue_moon\" title=\"IV. Nh\u1eefng c\u1ee5m t\u1eeb li\u00ean quan v\u00e0 tr\u00e1i ngh\u0129a v\u1edbi Once in a blue moon\">IV. Nh\u1eefng c\u1ee5m t\u1eeb li\u00ean quan v\u00e0 tr\u00e1i ngh\u0129a v\u1edbi Once in a blue moon<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/thecatalyst.edu.vn\/blogs\/once-in-a-blue-moon\/#V_Ung_dung_idiom_Once_in_a_blue_moon_trong_IELTS_Speaking_va_thuc_te\" title=\"V. \u1ee8ng d\u1ee5ng idiom Once in a blue moon trong IELTS Speaking v\u00e0 th\u1ef1c t\u1ebf\">V. \u1ee8ng d\u1ee5ng idiom Once in a blue moon trong IELTS Speaking v\u00e0 th\u1ef1c t\u1ebf<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/thecatalyst.edu.vn\/blogs\/once-in-a-blue-moon\/#51_Ung_dung_trong_IELTS_Speaking\" title=\"5.1. \u1ee8ng d\u1ee5ng trong IELTS Speaking\">5.1. \u1ee8ng d\u1ee5ng trong IELTS Speaking<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/thecatalyst.edu.vn\/blogs\/once-in-a-blue-moon\/#52_Ung_dung_trong_giao_tiep_thuc_te\" title=\"5.2. \u1ee8ng d\u1ee5ng trong giao ti\u1ebfp th\u1ef1c t\u1ebf\">5.2. \u1ee8ng d\u1ee5ng trong giao ti\u1ebfp th\u1ef1c t\u1ebf<\/a><\/li><\/ul><\/li><\/ul><\/nav><\/div>\n<p><span style=\"font-weight: 400;\">\u201cOnce in a blue moon\u201d l\u00e0 m\u1ed9t th\u00e0nh ng\u1eef ti\u1ebfng Anh kh\u00e1 th\u00fa v\u1ecb, nghe th\u00ec c\u00f3 v\u1ebb li\u00ean quan \u0111\u1ebfn hi\u1ec7n t\u01b0\u1ee3ng thi\u00ean nhi\u00ean hi\u1ebfm g\u1eb7p. Tuy nhi\u00ean, \u00fd ngh\u0129a th\u1ef1c s\u1ef1 c\u1ee7a c\u1ee5m t\u1eeb n\u00e0y l\u1ea1i mang t\u00ednh \u1ea9n d\u1ee5 nhi\u1ec1u h\u01a1n. V\u1eady once in a blue moon l\u00e0 g\u00ec v\u00e0 \u0111\u01b0\u1ee3c d\u00f9ng trong nh\u1eefng t\u00ecnh hu\u1ed1ng n\u00e0o? N\u1ebfu b\u1ea1n v\u1eabn c\u00f2n m\u01a1 h\u1ed3 th\u00ec h\u00e3y c\u00f9ng <\/span><a href=\"https:\/\/thecatalyst.edu.vn\/\"><b>The Catalyst for English<\/b><\/a><span style=\"font-weight: 400;\"> t\u00ecm hi\u1ec3u chi ti\u1ebft \u00fd ngh\u0129a c\u1ee5m t\u1eeb n\u00e0y ngay trong b\u00e0i vi\u1ebft d\u01b0\u1edbi \u0111\u00e2y nh\u00e9!<\/span><\/p>\n<h2><span class=\"ez-toc-section\" id=\"I_Once_in_a_blue_moon_nghia_la_gi\"><\/span><b>I. Once in a blue moon ngh\u0129a l\u00e0 g\u00ec?<\/b><span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p><span style=\"font-weight: 400;\">Theo t\u1eeb \u0111i\u1ec3n Cambridge, \u201conce in a blue moon\u201d \u0111\u01b0\u1ee3c \u0111\u1ecbnh ngh\u0129a l\u00e0 \u201cnot very often\u201d, t\u1ee9c l\u00e0 ch\u1ec9 nh\u1eefng \u0111i\u1ec1u x\u1ea3y ra r\u1ea5t hi\u1ebfm khi. So v\u1edbi c\u00e1c tr\u1ea1ng t\u1eeb th\u00f4ng th\u01b0\u1eddng, th\u00e0nh ng\u1eef n\u00e0y mang s\u1eafc th\u00e1i h\u00ecnh t\u01b0\u1ee3ng h\u01a1n, gi\u00fap c\u00e2u n\u00f3i tr\u1edf n\u00ean sinh \u0111\u1ed9ng h\u01a1n. Ng\u01b0\u1eddi ta th\u01b0\u1eddng d\u00f9ng c\u1ee5m n\u00e0y \u0111\u1ec3 than phi\u1ec1n khi ai \u0111\u00f3 \u00edt li\u00ean l\u1ea1c, ho\u1eb7c \u0111\u1ec3 n\u00f3i v\u1ec1 m\u1ed9t vi\u1ec7c \u0111\u1eb7c bi\u1ec7t m\u00e0 l\u00e2u l\u00e2u m\u1edbi l\u00e0m m\u1ed9t l\u1ea7n.<\/span><\/p>\n<p><b>V\u00ed d\u1ee5: <\/b><span style=\"font-weight: 400;\">My brother lives in Canada, so I only see him once in a blue moon. (Anh trai t\u00f4i s\u1ed1ng \u1edf Canada, n\u00ean hi\u1ebfm khi l\u1eafm t\u00f4i m\u1edbi g\u1eb7p anh \u1ea5y m\u1ed9t l\u1ea7n.)<\/span><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" width=\"1728\" height=\"1080\" class=\"alignnone size-full wp-image-7810\" src=\"https:\/\/thecatalyst.edu.vn\/blogs\/wp-content\/uploads\/2026\/03\/once-in-a-blue-moon-la-gi.jpg\" alt=\"&quot;&lt;\/p\" srcset=\"https:\/\/thecatalyst.edu.vn\/blogs\/wp-content\/uploads\/2026\/03\/once-in-a-blue-moon-la-gi.jpg 1728w, https:\/\/thecatalyst.edu.vn\/blogs\/wp-content\/uploads\/2026\/03\/once-in-a-blue-moon-la-gi-300x188.jpg 300w, https:\/\/thecatalyst.edu.vn\/blogs\/wp-content\/uploads\/2026\/03\/once-in-a-blue-moon-la-gi-1024x640.jpg 1024w, https:\/\/thecatalyst.edu.vn\/blogs\/wp-content\/uploads\/2026\/03\/once-in-a-blue-moon-la-gi-768x480.jpg 768w, https:\/\/thecatalyst.edu.vn\/blogs\/wp-content\/uploads\/2026\/03\/once-in-a-blue-moon-la-gi-1536x960.jpg 1536w\" sizes=\"(max-width: 1728px) 100vw, 1728px\" \/><\/p>\n<h2><span class=\"ez-toc-section\" id=\"II_Nguon_goc_cua_thanh_ngu_Once_in_a_blue_moon\"><\/span><b>II. Ngu\u1ed3n g\u1ed1c c\u1ee7a th\u00e0nh ng\u1eef Once in a blue moon<\/b><span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p><span style=\"font-weight: 400;\">Once in a blue moon idiom b\u1eaft ngu\u1ed3n t\u1eeb hi\u1ec7n t\u01b0\u1ee3ng thi\u00ean v\u0103n khi m\u1ed9t th\u00e1ng c\u00f3 2 l\u1ea7n tr\u0103ng tr\u00f2n, v\u00e0 l\u1ea7n th\u1ee9 hai \u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 \u201cBlue Moon\u201d. V\u00ec hi\u1ec7n t\u01b0\u1ee3ng n\u00e0y ch\u1ec9 x\u1ea3y ra kho\u1ea3ng 2,7 n\u0103m m\u1ed9t l\u1ea7n, n\u00ean n\u00f3 d\u1ea7n tr\u1edf th\u00e0nh bi\u1ec3u t\u01b0\u1ee3ng cho nh\u1eefng \u0111i\u1ec1u c\u1ef1c k\u1ef3 hi\u1ebfm. Ngo\u00e0i ra, trong m\u1ed9t s\u1ed1 \u0111i\u1ec1u ki\u1ec7n \u0111\u1eb7c bi\u1ec7t nh\u01b0 n\u00fai l\u1eeda phun tr\u00e0o hay ch\u00e1y r\u1eebng, m\u1eb7t tr\u0103ng c\u00f3 th\u1ec3 tr\u00f4ng nh\u01b0 m\u00e0u xanh do \u00e1nh s\u00e1ng b\u1ecb t\u00e1n x\u1ea1. Tuy nhi\u00ean, tr\u01b0\u1eddng h\u1ee3p n\u00e0y c\u00f2n hi\u1ebfm h\u01a1n r\u1ea5t nhi\u1ec1u.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">C\u1ee5m \u201conce in a blue moon\u201d \u0111\u00e3 tr\u1ea3i qua m\u1ed9t qu\u00e1 tr\u00ecnh thay \u0111\u1ed5i \u00fd ngh\u0129a kh\u00e1 th\u00fa v\u1ecb theo th\u1eddi gian. V\u00e0o th\u1ebf k\u1ef7 16, ng\u01b0\u1eddi ta d\u00f9ng h\u00ecnh \u1ea3nh \u201ctr\u0103ng m\u00e0u xanh\u201d \u0111\u1ec3 n\u00f3i v\u1ec1 nh\u1eefng \u0111i\u1ec1u ho\u00e0n to\u00e0n v\u00f4 l\u00fd, kh\u00f4ng th\u1ec3 x\u1ea3y ra, gi\u1ed1ng nh\u01b0 m\u1ed9t c\u00e1ch m\u1ec9a mai nh\u1eefng l\u1eddi n\u00f3i d\u1ed1i r\u00f5 r\u00e0ng. M\u1ed9t t\u00e0i li\u1ec7u n\u0103m 1528 \u0111\u00e3 vi\u1ebft: &#8220;If they say the moon is blue, we must believe that it is true&#8221; (N\u1ebfu h\u1ecd b\u1ea3o tr\u0103ng m\u00e0u xanh, ta c\u0169ng ph\u1ea3i tin \u0111\u00f3 l\u00e0 th\u1eadt) \u2013 nh\u1eb1m \u00e1m ch\u1ec9 nh\u1eefng l\u1eddi n\u00f3i d\u1ed1i tr\u1eafng tr\u1ee3n.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">\u0110\u1ebfn kho\u1ea3ng th\u1ebf k\u1ef7 19, \u00fd ngh\u0129a c\u1ee7a c\u1ee5m t\u1eeb b\u1eaft \u0111\u1ea7u thay \u0111\u1ed5i. Thay v\u00ec ch\u1ec9 nh\u1eefng \u0111i\u1ec1u kh\u00f4ng t\u01b0\u1edfng, n\u00f3 \u0111\u01b0\u1ee3c d\u00f9ng \u0111\u1ec3 n\u00f3i v\u1ec1 nh\u1eefng s\u1ef1 vi\u1ec7c v\u1eabn c\u00f3 th\u1ec3 x\u1ea3y ra nh\u01b0ng r\u1ea5t hi\u1ebfm g\u1eb7p. Sang th\u1ebf k\u1ef7 20, m\u1ed9t s\u1ef1 nh\u1ea7m l\u1eabn trong c\u00e1ch gi\u1ea3i th\u00edch l\u1ecbch thi\u00ean v\u0103n \u0111\u00e3 khi\u1ebfn \u201cBlue Moon\u201d \u0111\u01b0\u1ee3c hi\u1ec3u l\u00e0 l\u1ea7n tr\u0103ng tr\u00f2n th\u1ee9 hai trong m\u1ed9t th\u00e1ng. D\u00f9 kh\u00f4ng ho\u00e0n to\u00e0n ch\u00ednh x\u00e1c v\u1ec1 m\u1eb7t khoa h\u1ecdc, c\u00e1ch hi\u1ec3u n\u00e0y l\u1ea1i tr\u1edf n\u00ean ph\u1ed5 bi\u1ebfn v\u00e0 g\u00f3p ph\u1ea7n \u0111\u01b0a th\u00e0nh ng\u1eef \u201conce in a blue moon\u201d lan r\u1ed9ng nh\u01b0 ng\u00e0y nay.<\/span><\/p>\n<h2><span class=\"ez-toc-section\" id=\"III_Cach_su_dung_Once_in_a_blue_moon_trong_cau\"><\/span><b>III. C\u00e1ch s\u1eed d\u1ee5ng Once in a blue moon trong c\u00e2u<\/b><span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p><span style=\"font-weight: 400;\">\u201cOnce in a blue moon\u201d th\u01b0\u1eddng \u0111\u01b0\u1ee3c d\u00f9ng nh\u01b0 m\u1ed9t tr\u1ea1ng ng\u1eef ch\u1ec9 t\u1ea7n su\u1ea5t, mang \u00fd ngh\u0129a t\u01b0\u01a1ng t\u1ef1 \u201crarely\u201d ho\u1eb7c \u201chardly ever\u201d. C\u1ee5m t\u1eeb n\u00e0y kh\u00e1 linh ho\u1ea1t v\u1ec1 v\u1ecb tr\u00ed trong c\u00e2u, c\u00f3 th\u1ec3 \u0111\u1eb7t \u1edf \u0111\u1ea7u c\u00e2u \u0111\u1ec3 nh\u1ea5n m\u1ea1nh, chen v\u00e0o gi\u1eefa \u0111\u1ec3 b\u1ed5 sung \u00fd ngh\u0129a, ho\u1eb7c \u0111\u1ee9ng \u1edf cu\u1ed1i c\u00e2u \u0111\u1ec3 l\u00e0m r\u00f5 m\u1ee9c \u0111\u1ed9 hi\u1ebfm khi x\u1ea3y ra c\u1ee7a h\u00e0nh \u0111\u1ed9ng.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Once in a blue moon example:<\/span><\/p>\n<ul>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">I go to the cinema <\/span><b>once in a blue moon<\/b><span style=\"font-weight: 400;\"> because I\u2019m always busy.\u00a0<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><b>Once in a blue moon<\/b><span style=\"font-weight: 400;\">, my father treats us to a fancy dinner.<\/span><\/li>\n<\/ul>\n<p><img loading=\"lazy\" decoding=\"async\" width=\"1728\" height=\"1080\" class=\"alignnone size-full wp-image-7809\" src=\"https:\/\/thecatalyst.edu.vn\/blogs\/wp-content\/uploads\/2026\/03\/cach-dung-once-in-a-blue-moon.jpg\" alt=\"&quot;C\u00e1ch\" srcset=\"https:\/\/thecatalyst.edu.vn\/blogs\/wp-content\/uploads\/2026\/03\/cach-dung-once-in-a-blue-moon.jpg 1728w, https:\/\/thecatalyst.edu.vn\/blogs\/wp-content\/uploads\/2026\/03\/cach-dung-once-in-a-blue-moon-300x188.jpg 300w, https:\/\/thecatalyst.edu.vn\/blogs\/wp-content\/uploads\/2026\/03\/cach-dung-once-in-a-blue-moon-1024x640.jpg 1024w, https:\/\/thecatalyst.edu.vn\/blogs\/wp-content\/uploads\/2026\/03\/cach-dung-once-in-a-blue-moon-768x480.jpg 768w, https:\/\/thecatalyst.edu.vn\/blogs\/wp-content\/uploads\/2026\/03\/cach-dung-once-in-a-blue-moon-1536x960.jpg 1536w\" sizes=\"(max-width: 1728px) 100vw, 1728px\" \/><\/p>\n<h2><span class=\"ez-toc-section\" id=\"IV_Nhung_cum_tu_lien_quan_va_trai_nghia_voi_Once_in_a_blue_moon\"><\/span><b>IV. Nh\u1eefng c\u1ee5m t\u1eeb li\u00ean quan v\u00e0 tr\u00e1i ngh\u0129a v\u1edbi Once in a blue moon<\/b><span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p><span style=\"font-weight: 400;\">Trong ti\u1ebfng Anh, c\u00f3 kh\u00e1 nhi\u1ec1u t\u1eeb v\u00e0 c\u1ee5m t\u1eeb mang \u00fd ngh\u0129a t\u01b0\u01a1ng t\u1ef1 ho\u1eb7c tr\u00e1i ng\u01b0\u1ee3c v\u1edbi \u201conce in a blue moon\u201d. D\u01b0\u1edbi \u0111\u00e2y l\u00e0 m\u1ed9t v\u00e0i v\u00ed d\u1ee5 ti\u00eau bi\u1ec3u b\u1ea1n c\u00f3 th\u1ec3 tham kh\u1ea3o.<\/span><\/p>\n<table>\n<tbody>\n<tr>\n<td style=\"text-align: center;\"><b>T\u1eeb<\/b><\/td>\n<td style=\"text-align: center;\"><b>\u00dd ngh\u0129a<\/b><\/td>\n<td style=\"text-align: center;\"><b>V\u00ed d\u1ee5<\/b><\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: center;\" colspan=\"3\"><b>T\u1eeb\/ c\u1ee5m t\u1eeb li\u00ean quan<\/b><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400;\">Rarely<\/span><\/td>\n<td><span style=\"font-weight: 400;\">Hi\u1ebfm khi<\/span><\/td>\n<td><span style=\"font-weight: 400;\">She rarely watches television; she prefers reading books.<\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400;\">Seldom<\/span><\/td>\n<td><span style=\"font-weight: 400;\">\u00cdt khi, hi\u1ebfm khi<\/span><\/td>\n<td><span style=\"font-weight: 400;\">Success seldom comes to those who do not work hard.<\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400;\">Infrequently<\/span><\/td>\n<td><span style=\"font-weight: 400;\">Kh\u00f4ng th\u01b0\u1eddng xuy\u00ean<\/span><\/td>\n<td><span style=\"font-weight: 400;\">Buses run infrequently in this remote area, especially at night.<\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400;\">Hardly ever<\/span><\/td>\n<td><span style=\"font-weight: 400;\">H\u1ea7u nh\u01b0 kh\u00f4ng bao gi\u1edd<\/span><\/td>\n<td><span style=\"font-weight: 400;\">I hardly ever eat fast food because I care about my health.<\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400;\">On rare occasions<\/span><\/td>\n<td><span style=\"font-weight: 400;\">Trong nh\u1eefng d\u1ecbp hi\u1ebfm hoi<\/span><\/td>\n<td><span style=\"font-weight: 400;\">On rare occasions, the two rival companies collaborate on a project.<\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400;\">Once in a great while<\/span><\/td>\n<td><span style=\"font-weight: 400;\">C\u1ef1c k\u1ef3 hi\u1ebfm khi.<\/span><\/td>\n<td><span style=\"font-weight: 400;\">Once in a great while, a marketing campaign comes along that truly changes the industry&#8217;s landscape. (C\u1ef1c k\u1ef3 hi\u1ebfm khi m\u1edbi c\u00f3 m\u1ed9t chi\u1ebfn d\u1ecbch marketing th\u1ef1c s\u1ef1 thay \u0111\u1ed5i di\u1ec7n m\u1ea1o c\u1ee7a ng\u00e0nh.)<\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400;\">Every now and then<\/span><\/td>\n<td><span style=\"font-weight: 400;\">Th\u1ec9nh tho\u1ea3ng, \u0111\u00f4i khi<\/span><\/td>\n<td><span style=\"font-weight: 400;\">Even though I eat healthily, I still enjoy a piece of chocolate cake every now and then. (M\u1eb7c d\u00f9 t\u00f4i \u0103n u\u1ed1ng l\u00e0nh m\u1ea1nh, t\u00f4i v\u1eabn th\u01b0\u1edfng th\u1ee9c m\u1ed9t mi\u1ebfng b\u00e1nh socola th\u1ec9nh tho\u1ea3ng.)<\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400;\">From time to time<\/span><\/td>\n<td><span style=\"font-weight: 400;\">\u0110\u00f4i l\u00fac, thi tho\u1ea3ng<\/span><\/td>\n<td><span style=\"font-weight: 400;\">e still meet for coffee from time to time to discuss SEO trends and website audits. (Ch\u00fang t\u00f4i v\u1eabn g\u1eb7p nhau u\u1ed1ng c\u00e0 ph\u00ea \u0111\u00f4i l\u00fac \u0111\u1ec3 th\u1ea3o lu\u1eadn v\u1ec1 c\u00e1c xu h\u01b0\u1edbng SEO v\u00e0 ki\u1ec3m \u0111\u1ecbnh website.)<\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400;\">Now and again<\/span><\/td>\n<td><span style=\"font-weight: 400;\">\u0110\u00f4i khi<\/span><\/td>\n<td><span style=\"font-weight: 400;\">Everyone feels a bit overwhelmed with work now and again. (Ai c\u0169ng c\u1ea3m th\u1ea5y \u0111\u00f4i ch\u00fat \u00e1p l\u1ef1c v\u1edbi c\u00f4ng vi\u1ec7c v\u00e0o nh\u1eefng l\u00fac n\u00e0y l\u00fac kh\u00e1c.)<\/span><\/td>\n<\/tr>\n<tr>\n<td colspan=\"3\">\n<p style=\"text-align: center;\"><b>Tr\u00e1i ngh\u0129a<\/b><\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400;\">Very often<\/span><\/td>\n<td><span style=\"font-weight: 400;\">R\u1ea5t th\u01b0\u1eddng xuy\u00ean.<\/span><\/td>\n<td><span style=\"font-weight: 400;\">I visit my grandparents very often, usually every weekend.<\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400;\">Frequently<\/span><\/td>\n<td><span style=\"font-weight: 400;\">Th\u01b0\u1eddng xuy\u00ean<\/span><\/td>\n<td><span style=\"font-weight: 400;\">The website is frequently updated with new SEO tips.<\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400;\">Regularly<\/span><\/td>\n<td><span style=\"font-weight: 400;\">\u0110\u1ec1u \u0111\u1eb7n<\/span><\/td>\n<td><span style=\"font-weight: 400;\">You should exercise regularly to maintain a healthy weight.<\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400;\">Constantly<\/span><\/td>\n<td><span style=\"font-weight: 400;\">Li\u00ean t\u1ee5c, kh\u00f4ng ng\u1eebng<\/span><\/td>\n<td><span style=\"font-weight: 400;\">The world of digital marketing is constantly changing.<\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400;\">All the time<\/span><\/td>\n<td><span style=\"font-weight: 400;\">Su\u1ed1t ng\u00e0y, m\u1ecdi l\u00fac<\/span><\/td>\n<td><span style=\"font-weight: 400;\">He complains about his job all the time but never quits.<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h2><span class=\"ez-toc-section\" id=\"V_Ung_dung_idiom_Once_in_a_blue_moon_trong_IELTS_Speaking_va_thuc_te\"><\/span><b>V. \u1ee8ng d\u1ee5ng idiom Once in a blue moon trong IELTS Speaking v\u00e0 th\u1ef1c t\u1ebf<\/b><span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p><span style=\"font-weight: 400;\">Vi\u1ec7c s\u1eed d\u1ee5ng th\u00e0nh ng\u1eef kh\u00f4ng ch\u1ec9 l\u00e0 h\u1ecdc thu\u1ed9c l\u00f2ng m\u00e0 l\u00e0 bi\u1ebft \u0111\u01b0a v\u00e0o \u0111\u00fang ch\u1ed7, \u0111\u00fang l\u00fac. D\u01b0\u1edbi \u0111\u00e2y l\u00e0 c\u00e1ch \u1ee9ng d\u1ee5ng th\u00e0nh ng\u1eef n\u00e0y trong b\u00e0i thi <a href=\"https:\/\/thecatalyst.edu.vn\/blogs\/hoc-ielts\/ielts-speaking\"><strong>IELTS Speaking<\/strong><\/a> c\u0169ng nh\u01b0 giao ti\u1ebfp h\u1eb1ng ng\u00e0y:<\/span><\/p>\n<h3><span class=\"ez-toc-section\" id=\"51_Ung_dung_trong_IELTS_Speaking\"><\/span><b>5.1. \u1ee8ng d\u1ee5ng trong IELTS Speaking<\/b><span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p><span style=\"font-weight: 400;\">Trong k\u1ef3 thi IELTS, gi\u00e1m kh\u1ea3o kh\u00f4ng t\u00ecm ki\u1ebfm nh\u1eefng th\u00ed sinh h\u1ecdc v\u1eb9t. H\u1ecd t\u00ecm ki\u1ebfm s\u1ef1 linh ho\u1ea1t trong ng\u00f4n ng\u1eef. V\u00ed d\u1ee5 v\u1edbi part 1, tr\u1ea3 l\u1eddi c\u00e1c c\u00e2u h\u1ecfi v\u1ec1 th\u00f3i quen (Frequency). Thay v\u00ec ch\u1ec9 n\u00f3i &#8220;I rarely go to the cinema&#8221;, b\u1ea1n h\u00e3y n\u00e2ng c\u1ea5p c\u00e2u tr\u1ea3 l\u1eddi nh\u01b0 sau \u0111\u1ec3 \u0111\u1ea1t band 7.0+:<\/span><\/p>\n<ul>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><b>C\u00e2u h\u1ecfi: <\/b><span style=\"font-weight: 400;\">Do you often go to the cinema?<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><b>Tr\u1ea3 l\u1eddi: <\/b><span style=\"font-weight: 400;\">To be honest, once in a blue moon. Since I started my new job in marketing, I\u2019ve been snowed under with work, so I hardly have any spare time for movies.<\/span><\/li>\n<\/ul>\n<p><span style=\"font-weight: 400;\">Part 2: M\u00f4 t\u1ea3 m\u1ed9t s\u1ef1 ki\u1ec7n ho\u1eb7c tr\u1ea3i nghi\u1ec7m hi\u1ebfm hoi<\/span><\/p>\n<ul>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><b>Ng\u1eef c\u1ea3nh:<\/b><span style=\"font-weight: 400;\"> Describe a family member you spend time with.<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><b>Tri\u1ec3n khai:<\/b><span style=\"font-weight: 400;\"> &#8220;&#8230;My cousin Linh lives in a different province, so we only get to see each other once in a blue moon. However, every time we meet, we spend hours shopping and catching up&#8230;&#8221;<\/span><\/li>\n<\/ul>\n<h3><span class=\"ez-toc-section\" id=\"52_Ung_dung_trong_giao_tiep_thuc_te\"><\/span><b>5.2. \u1ee8ng d\u1ee5ng trong giao ti\u1ebfp th\u1ef1c t\u1ebf<\/b><span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p><b>Alex:<\/b><span style=\"font-weight: 400;\"> &#8220;Wait, is that a homemade salad? Since when do you meal prep, Sam?&#8221;<\/span><\/p>\n<p><b>Sam:<\/b><span style=\"font-weight: 400;\"> &#8220;Oh, shut up! (Laughing) I know, I know. I only cook at home <\/span><b>once in a blue moon<\/b><span style=\"font-weight: 400;\">, but I\u2019m trying to be a bit more health-conscious this month.&#8221;<\/span><\/p>\n<p><b>Alex:<\/b><span style=\"font-weight: 400;\"> &#8220;I\u2019m impressed! Usually, getting you to eat anything green is like pulling teeth. What changed?&#8221;<\/span><\/p>\n<p><b>Sam: <\/b><span style=\"font-weight: 400;\">&#8220;Honestly? I looked at my bank statement and realized I was spending way too much on takeout. I used to save home-cooked meals for once in a blue moon, but my wallet can\u2019t take it anymore.&#8221;<\/span><\/p>\n<p><b>Alex: <\/b><span style=\"font-weight: 400;\">&#8220;Fair enough. Well, enjoy it while it lasts! I give it a week before we&#8217;re back at the burger joint.&#8221;<\/span><\/p>\n<p><b>Sam: <\/b><span style=\"font-weight: 400;\">&#8220;Hey, have a little faith! Though&#8230; I wouldn&#8217;t bet against you.&#8221;<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Tr\u00ean \u0111\u00e2y l\u00e0 to\u00e0n b\u1ed9 nh\u1eefng ki\u1ebfn th\u1ee9c quan tr\u1ecdng gi\u00fap b\u1ea1n hi\u1ec3u r\u00f5 \u201conce in a blue moon l\u00e0 g\u00ec\u201d, t\u1eeb \u00fd ngh\u0129a, ngu\u1ed3n g\u1ed1c \u0111\u1ebfn c\u00e1ch s\u1eed d\u1ee5ng trong th\u1ef1c t\u1ebf. Hy v\u1ecdng sau b\u00e0i vi\u1ebft n\u00e0y, b\u1ea1n c\u00f3 th\u1ec3 t\u1ef1 tin \u00e1p d\u1ee5ng th\u00e0nh ng\u1eef n\u00e0y m\u1ed9t c\u00e1ch t\u1ef1 nhi\u00ean khi giao ti\u1ebfp ti\u1ebfng Anh. \u0110\u1ed3ng th\u1eddi, \u0111\u1eebng qu\u00ean theo d\u00f5i danh m\u1ee5c <\/span><a href=\"https:\/\/thecatalyst.edu.vn\/blogs\/hoc-tieng-anh\/tu-vung-tieng-anh\"><b>t\u1eeb v\u1ef1ng Ti\u1ebfng Anh<\/b><\/a><span style=\"font-weight: 400;\"> t\u1ea1i The Catalyst for English \u0111\u1ec3 kh\u00e1m ph\u00e1 th\u00eam nhi\u1ec1u b\u00e0i vi\u1ebft v\u1ec1 t\u1eeb v\u1ef1ng h\u1eefu \u00edch nh\u00e9!<\/span><\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u201cOnce in a blue moon\u201d l\u00e0 m\u1ed9t th\u00e0nh ng\u1eef ti\u1ebfng Anh kh\u00e1 th\u00fa v\u1ecb, nghe th\u00ec c\u00f3 v\u1ebb li\u00ean quan \u0111\u1ebfn hi\u1ec7n t\u01b0\u1ee3ng thi\u00ean nhi\u00ean hi\u1ebfm g\u1eb7p. Tuy nhi\u00ean, \u00fd ngh\u0129a th\u1ef1c s\u1ef1 c\u1ee7a c\u1ee5m t\u1eeb n\u00e0y l\u1ea1i mang t\u00ednh \u1ea9n d\u1ee5 nhi\u1ec1u h\u01a1n. V\u1eady once in a blue moon l\u00e0 g\u00ec v\u00e0 \u0111\u01b0\u1ee3c d\u00f9ng [&hellip;]<\/p>\n","protected":false},"author":7,"featured_media":7811,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[38,51,48],"tags":[],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO Premium plugin v22.0 (Yoast SEO v22.8) - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>\u00dd ngh\u0129a v\u00e0 c\u00e1ch d\u00f9ng c\u1ee7a Once In A Blue Moon chi ti\u1ebft<\/title>\n<meta name=\"description\" content=\"T\u00ecm hi\u1ec3u \u00fd ngh\u0129a v\u00e0 c\u00e1ch d\u00f9ng c\u1ee7a idiom Once in a blue moon chi ti\u1ebft, k\u00e8m v\u00ed d\u1ee5 gi\u00fap b\u1ea1n \u00e1p d\u1ee5ng t\u1ef1 nhi\u00ean c\u00f9ng The Catalyst for English.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/thecatalyst.edu.vn\/blogs\/once-in-a-blue-moon\" \/>\n<meta property=\"og:locale\" content=\"vi_VN\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Once In A Blue Moon l\u00e0 g\u00ec? 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