问题

I can’t get through to the general manager’s office anyhow. —— The line is busy. Someone＿＿＿＿＿the telephone.

A:must use
B:uses
C:must have been using
D:must be using

正确答案是：

同类题型

There is a wooden bridge ______the river_______ my house.

In developed countries, farm workers _________ only a small section of the population.

Did you buy ______for your parents

_________，so he didn’t come to school last week.

Jack is a good friend _______, and he often comes to our home for a visit.