单项选择题

It's high time we（）something to stop air pollution.

A．are doing
B．did
C．have to do
D．must do

<上一题目录下一题>

热门试题

单项选择题

We agreed to accept（）they thought was the best tourist guide.

A．whatever
B．whomever
C．whichever
D．whoever

单项选择题

It was not until he arrived at the station（）he realized he had forgotten his ticket.

A．when
B．that
C．for
D．in

相关试题