Mothers begin licking their kittens 18 birth---to clean them, stimulate the release of body waste, wake them up to suck milk, and provide comfort.
答案：(B) right after
【句型】right after 字詞搭配「緊接在……之後」，表示「母貓從出生後就開始舔舐小貓」；out of（從……）、just before（就在……之前，時間方向相反）、along with（伴隨）都不合。
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四個選項都是介系詞，其中兩個前面還帶了一個副詞，而 just before（就在……之前）與 right after（就在……之後）只差方向，如果沒把破折號後面那一串讀完，很容易挑反。
四個選項都是介系詞，可見這一格考的是語意與時間方向。順帶把一件事分清楚：這四個選項剛好分成兩型。out of 與 along with 是幾個字合起來當一個介系詞用，中間拆不開；just before 與 right after 則是「副詞加介系詞」，前面那個字只是修飾語，真正管事的是後面的 before 與 after。驗算法是把前面那個字拿掉——just before birth 拿掉 just 仍是 before birth，句子照樣成立；along with 拿掉 along 就不成句。劍橋 English Grammar Today 的 Prepositional phrases 條目說，副詞可以放在介系詞前面修飾它，主要用在可分級的時間或地點介系詞上，條目列出的字裡就有 before。整句是 Mothers begin licking their kittens ___ birth——母貓從什麼時候開始舔幼貓？決定性的線索在破折號後面：to clean them, stimulate the release of body waste, wake them up to suck milk, and provide comfort（清潔幼貓、刺激牠們排便、叫醒牠們吸奶、給予安撫）。這四件事全都要等幼貓出生之後才做得了——還沒出生就談不上清潔、排便或吸奶，所以填 right after（緊接在……之後）。right 在這裡是用來加強介系詞的副詞，意思是「就在、緊接著」，同一組還有 right before（就在之前）、right now（就是現在）、right here（就在這裡）。
just before（就在……之前）：時間方向剛好相反，與破折號後面那四件事直接衝突。out of（從……出來）：out of birth 不是通行的說法。along with（連同、伴隨）：講的是同時附帶的東西，不是時間的先後。
right after（緊接在……之後）、right before（就在……之前）、right now（就是現在）、give birth to（生下）、stimulate（刺激）、provide comfort（給予安撫）。
When it comes to personal hygiene, cats are the best example of cleanliness. They are naturally equipped with 16 they need to groom themselves: a flexible tongue with which to lick, forepaws they moisten with saliva and use like washcloths, and teeth to dig out tougher pieces of food. 17, adult cats may spend as much as half of their waking hours grooming themselves, their relatives and friends.
Mothers begin licking their kittens 18 birth---to clean them, stimulate the release of body waste, wake them up to suck milk, and provide comfort. Kittens usually begin grooming themselves when they are about four weeks old. 19 five weeks of age, kittens also begin grooming other baby cats, as well as their mom.
20 grooming among cats, called allogrooming, often continues into adulthood. Allogrooming is a social activity that serves to strengthen the bond between cats.