The crazy fans___________ patiently for two hours, and they will wait till the movie star arrives.
| A．are waiting | B．had waited |
| C．have been waiting | D．will wait |
_________ found my wallet, Tom?
| A．Where did you that | B．Where was it you |
| C．Where have you that | D．Where was it that you |
It was not until 1920_________ regular radio broadcast began.
| A．while | B．which |
| C．that | D．Since |
It was in the factory _________ produced TV sets _________ I got to know her.
| A．which; which | B．that; which |
| C．that ；that | D．where ； that |
Factory workers have to work very hard, and _________.
| A．farmers do so | B．farmers work so |
| C．so have farmers | D．so do farmers |
Only when David did it a second time _________.
| A．he realized his mistake |
| B．he was realizing his mistake |
| C．did he realize his mistake |
| D．he did realize his mistake |