时间状语从句和if引导的真实条件句可以有哪些时态？主句若是过去时，从句会不会有用到过去完成时表过去已完成。

【答】

第一问：根据需要，从句可以有多种时态，如：一般现在时、现在进行时、现在完成时、一般过去时、过去进行时、过去完成时等。

第二问：主句若是过去时，根据需要，从句可以用过去完成时。例如：

He told me to wait until the manager had come back.

He went to his granny's as soon as he had finished my homework.

Tom was black and blue after he had fallen down the stairs.

The girl repeated the poem after I had read it twice.

The hen cackled when she had laid an egg.

She promised me to return the book if she had finished reading it.

Mother said that I could watch TV as long as I had finished my homework.