1.When+现在分词.例如:

When sleeping,I never hear a thing.睡觉时,我什么都听不见.

2.When+过去分词.例如:

This dictionary will look nice when printed.这本词典印出来时会很好看.

3.When+名词或形容词.例如:

When a boy,he was sick all the time.小的时候,他经常生病.

4.When+介词短语.例如:

When at Rome do as the Romans do.入乡随俗.

When的四个高级用法技巧