If you want to talk to your teacher,you should _____first.A.to call her up B.call her up 为什么?

问题描述:

If you want to talk to your teacher,you should _____first.
A.to call her up B.call her up 为什么?

B should情态动词,后面直接跟动词原形,不需要加to.

B should后用动词原形

B
should情态动词,后面跟动词原形