1、It is + 时间段 + since… 的意思是“自从……以来有一段时间了”。
2、It is + 时间点 + when… 的意思是“当……的时候时间是……”。
3、It is + 时间段 + before… 的意思是“在……之前有一段时间”。
It was past one o’clock when he came in. 他回来时已经一点多了。
It won’t be long before they understand each other. 过不了多久他们就会互相了解的。
It was long before she came back. 没过很久她才回来了。
It will be long before we meet again. 很久以后我们才会再见面。
It will be five years before he meets you again. 五年之后他就会再见你的。
It is / has been four days since I caught a cold. 我感冒已四天了。
It is / has been two weeks since we met last. 自从我们上次见面以来已过了两周。
It is/ has been three years since his brother joined the army. 他哥哥入伍三年了。
It is/ has been three years since his brother left the army. 他哥哥退伍三年了。
It is/ has been twenty minutes since he got here. 他到这儿已经二十分钟了。
It is/ has been ten years since they got married. 他们结婚到现在已经十年了。
It won’t be long before we get ready for the travel. 不久后我们就能做好旅行的准备工作了。
It will be three years before we meet again. 三年以后我们才能再次相见。
It had been an hour before he finished his work. 一个小时以后他才完成了工作。
It is an hour since he finished his work. 他完成工作（到现在）已经一个小时了。
It was about ten minutes since he had come here. 他在这儿待了约有十分钟。
It’s been a while since the family had an outing together. 家人好久没一同出游了.
It won’t be long before a new factory is built in our hometown.很快一座新工厂要在我们家乡建造。
It was not long before a helicopter arrived on the scene to rescue the survivors of the plane crash.不久，一架直升飞机到达机场.
2、It is + 时间点 + when… 的意思是“当……的时候时间是……”。
3、It is + 时间段 + before… 的意思是“在……之前有一段时间”。
It was past one o’clock when he came in. 他回来时已经一点多了。
It won’t be long before they understand each other. 过不了多久他们就会互相了解的。
It was long before she came back. 没过很久她才回来了。
It will be long before we meet again. 很久以后我们才会再见面。
It will be five years before he meets you again. 五年之后他就会再见你的。
It is / has been four days since I caught a cold. 我感冒已四天了。
It is / has been two weeks since we met last. 自从我们上次见面以来已过了两周。
It is/ has been three years since his brother joined the army. 他哥哥入伍三年了。
It is/ has been three years since his brother left the army. 他哥哥退伍三年了。
It is/ has been twenty minutes since he got here. 他到这儿已经二十分钟了。
It is/ has been ten years since they got married. 他们结婚到现在已经十年了。
It won’t be long before we get ready for the travel. 不久后我们就能做好旅行的准备工作了。
It will be three years before we meet again. 三年以后我们才能再次相见。
It had been an hour before he finished his work. 一个小时以后他才完成了工作。
It is an hour since he finished his work. 他完成工作（到现在）已经一个小时了。
It was about ten minutes since he had come here. 他在这儿待了约有十分钟。
It’s been a while since the family had an outing together. 家人好久没一同出游了.
It won’t be long before a new factory is built in our hometown.很快一座新工厂要在我们家乡建造。
It was not long before a helicopter arrived on the scene to rescue the survivors of the plane crash.不久，一架直升飞机到达机场.
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第1个回答 2013-12-08
有道词典
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