英语中“复合谓语”如何构成?请大神解答的通俗易懂些.另外：be动词为系动词,不能单独作谓语,那么

第一种是由情态动词或助动词+不带to的动词不定式构成的复合谓语：
What does this word mean?
I must do it at once
He can finish it in time
第二种是由连系动词+表语构成的复合谓语.例如：
You look tired.
We are all at home.
. Keep quite please.
I feel cold
They remain quiet in the room