2015年衛(wèi)生類職稱英語(yǔ)考試語(yǔ)法知識(shí)：before和after引導(dǎo)的時(shí)間狀語(yǔ)從句

由before和after引導(dǎo)的時(shí)間狀語(yǔ)從句。

注意before引導(dǎo)的從句不再用否定式的謂語(yǔ)，主句用將來(lái)時(shí)，從句總是用現(xiàn)在時(shí);如果before引導(dǎo)的從句謂語(yǔ)用的是過(guò)去時(shí)，則主句動(dòng)詞多用過(guò)去完成時(shí)或者一般過(guò)去時(shí)，根據(jù)情況可翻譯成“...才....”，“....就....”，“....還沒(méi)....”，“...趁著....”“然后...." 等。After表示主句動(dòng)作發(fā)生在從句動(dòng)作之后。主句和從句的動(dòng)作的時(shí)間關(guān)系正好與before引導(dǎo)的從句相反。例如：

It will be four days before they come back. (...才....)

It wasn't long before they got arrested by the policemen.(就)

Einstein almost knocked me down before he saw me.(才)

My father had left for Canada just before the letter arrived.(才)

They had not been married four months before they were divorced.(就)

Think before you leap.(然后)

He had gone out of the door before I could say a single word of it.(還沒(méi))

Do it before it gets worse.(趁著)

Eat it before the food gets cold.(趁著)

Don't let me know what you decide beforeyou think it over.

After you think it over, please let me know what you decide.

After we had finished the work, we went home.(從句用過(guò)去完成時(shí)，主句用一般過(guò)去時(shí))