问题

They were surprised that a child should work out the problem ________ they themselves couldn’t

A:once
B:then
C:While
D:if

正确答案是：

同类题型

The brothers’ doubt is ______ Henry can stay out of jail.

omenagood salary in a job instead of staying home, but they decided not to work forthe sake of the family.

There____adesk,twobedsandfourchairsintheroom

_______ are you going to visit the sciencemuseum—Next Saturday.

_______ buy your ticket from a ticket machine. There are lots of people there.