问题

Only after he had spent several nightsworking on the math problem _______ to wonder whether the problem was wronglyset.

A:to study
B:did he begin
C:then he began
D:so that he began

正确答案是：

同类题型

________ people are taking action to protectthe environment now.— Yes. ________ of my classmates come to school bybike now.

The little girl,but her family was too poor at that time.

It’s nearly seven o’clock. Jack__________ be here at any moment.[ ]

－I’ll come to see your performance at 9:00 tomorrow morning.－I’m sorry, by then my performance ______ and I _______ reporters in the meeting room

I shall never forget those years ____ I lived in the country with the farmers, ____ has a great effect on my life.