【所有问题】如果主句的宾语是个宾语从句，那么 would have done 是用在主句中充当谓语还是主句的宾语从句中充当谓语？如果用在主句中充当谓语，那么宾语从句的谓语用什么形式？如果是用在宾语从句中充当谓语，那么主句谓语用什么形式？如果虚拟条件句中的宾语为宾语从句，那么条件句中谓语用什么形式？条件句中的宾语从句又用什么形式？

现在，分别解答如下：

【问】1. 如果主句的宾语是个宾语从句，那么would have done 是用在主句中充当谓语，还是主句的宾语从句中充当谓语？

【答】would have done用在主句中，宾语从句用陈述语气。

【问】2. 如果用在主句中充当谓语，那么宾语从句的谓语用什么形式？

【答】宾语从句仍用陈述语气。根据语境需要，宾语从句一般使用“过去范畴的时态”：一般过去时，过去完成时，过去进行时、过去将来时等。如：

If you had come earlier, you would have seen what had happened.

即便不用虚拟语气，宾语从句也用过去完成时：You saw what had happened.

If you had asked him, he would have told you that he would refuse to help.

即便不用虚拟语气，宾语从句也用过去将来时：He told you that he would reuse to help.

【问】3. 如果是用在宾语从句中充当谓语，那么主句谓语用什么形式？

【答】这个问题不成立。

【问】4. 如果虚拟条件句中的宾语为宾语从句，那么条件句中谓语用什么形式？

【答】条件句中的谓语形式是had done，跟主句的would have done对应。

【问】5. 如果虚拟条件句中的宾语为宾语从句，条件句中的宾语从句又用什么形式？

【答】虚拟条件句中含有宾语从句时，宾语从句仍然是陈述语气（跟主句中的宾语从句一样对待。）例如：

If I had known that she would come, I would have gone to meet her.

即便不用虚拟语气，宾语从句也用过去将来时：I knew that she would come.