He has made a discovery, _________ of great importance to the progress of science and technology．
| A．I think which is | B．which I think is |
| C．which I think it | D．which I think it is |
The police chief ordered that parking on Main Street during the rush hours.
| A．be prohibiting |
| B．is prohibited |
| C．was prohibited |
| D．be prohibited |
I it to him if I thought he would not understand.
| A．shall explain |
| B．will explain |
| C．would explain |
| D．explain |
The housemaster was strict. He requested that we television on weekdays’ nights.
| A．not watch |
| B．not to watch |
| C．not be watching |
| D．have not watched |
I was in a hurry that day. Otherwise I to talk to you.
| A．had stopped |
| B．would have stopped |
| C．stopped |
| D．had to stop |
Without electronic computers, much of today’s advanced technology achieved.
| A．must have been |
| B．could have been |
| C．should have |
| D．would not be |