John cannot but____his teacher to help him solve the difficult problems.A.to ask B.ask C.asking D.asked 详解.

分类: 作业答案 • 2022-05-18 17:21:42

问题描述：

John cannot but____his teacher to help him solve the difficult problems.
A.to ask B.ask C.asking D.asked 详解.

答

B. cannot but 不得不,后面接动词原型