clauses of purpose(目的状语从句)

引导目的状语从句的连词有 so, so that, in order that 和 that。目的状语从句的显著特点之一，就是使用情态动词。根据 R. Quirk 等人的说法，目的状语从句通常使用 can, could, may, might, should, would 等情态动词。

A. so 通常用于不大正式的语体中:

1. She whispered to me so no one else would hear. 她低声跟我说话以免别人听见。

2. I'll put it in my diary straight away so I won't forget. 我马上把它记在日记里，以免忘记。

3. Let the dog loose, so it can have a run. 把狗放开，让它跑一跑。

B. so that 较多用于正式语体:

1. I'll wash this dress so that you can wear it. 我要把这条连衣裙洗一洗好让你穿。

2. The door was open, so that anyone passing could look in. 门开着，以便让所有的过路人都能往里面看。

C. in order that 用于相当正式的语体, 表示经过精心策划的目的, 有时可与 so that 互换:

1. Come early in order that you may see him. 早点来以便能见到他。

2. He left early in order that he should/would/might arrive on time. 他早早动身，以便按时到达。

D. that 是个古体, 因而用得较少:

He died that others might live. 他死了,为的是让别人活着。