(1)在一般现在时态(do/does/am/is/are)，一般过去时态(did/was/were)中，谓语动词/系动词be就是限定动词。

Tom likes playing computer games.

Jack lost his wallet yesterday.

Tom is a very clever boy.

I am taller than Tom

They are from the same school.

(2)在现在进行时态(am/is/are/+doing，过去进行时态中(was/were+doing)，助动词be就是限定动词。

Tom is doing her homework.

They are playing basketball.

(3)在完成时态have/has done，现在完成进行时态中have/has been doing，助动词have/has就是限定动词。

They have seen the film.

She has seen the film.

Tom has been playing computer games for two hours.

They have been watching TV for three hours.

(4)在过去完成时态had done，过去完成进行时态had been doing，助动词had不受人称和数限制，但是处于第1动词位置。

Tom had studied English before he went to America.

We had learned French before we went to France.

(5)在一般将来时态be going to/will +动词原形，be为限定动词,助动词will不受主语制约，但是处于第1动词位置。

She is going to visit Franche next Monday.

We are going to visit Beijing next Monday.

Tom will go to Guangzhou this afternoon.

I will go to Guangzhou this afternoon

(6)含有情态动词句子，情态动词不受主语和人称数的限制，但是处于第1动词位置。

She can speak English.

I can speak English.

He can speak English.

She must be at home

She must have gone home

They may be in the room.

Tom can't have been to America.

They can't have gone to America