過去時(shí)
在...期間的某一時(shí)候
They met and fell in love with each other during the Second World War.
他們在第二次世界大戰(zhàn)期間相遇并相愛.為什么不用過去完成時(shí)？因?yàn)檫@個(gè)動(dòng)作完成需要時(shí)間，時(shí)間一動(dòng)就成一種狀態(tài)了嘎嘎in(表示時(shí)間)在…時(shí)期, 在…之后, 在過程中 In her twenties and thirties she had had no difficulty getting jobs.她在二三十歲時(shí)找工作一點(diǎn)也不困難。I cannot see you now, come back in half an hour.我現(xiàn)在不能見你, 半小時(shí)后回來。on(表示時(shí)間)在…之時(shí) It occurred on the morning of the fifteenth.事情發(fā)生在15號(hào)的上午。On arriving home, I was met by my daughter.到家時(shí)我的女兒出來迎接我。at(表示時(shí)間)在, 在…時(shí)刻[時(shí)辰, 期間, 階段, 時(shí)節(jié)]; 在…歲時(shí) The meeting will open at 15 ∶ 00.會(huì)議在下午三點(diǎn)鐘開始。during1、(表示時(shí)間)在某情況的一段時(shí)間 Where shall you go during the summer?今年夏天你將到什么地方去?2、(表示時(shí)間)在…期間, 當(dāng)…之時(shí), 在…期間的某個(gè)時(shí)候 The fire started during the workmen's dinner.火災(zāi)是在工人們吃飯時(shí)發(fā)生的。