Just as sound travels through the air in waves, electricity travels through the air in ______ radio waves.
| A．what is called | B．which is called | C．what it is called | D．which it is called |
The president hopes that the people will be better off when he quits than when he _____．
| A．has started | B．starts |
| C．started | D．will start |
_____ something to drink, as the movie will last three hours．
| A．Grab | B．To grab |
| C．Grabbing | D．Grabbed |
The manager is said to have arrived back from Paris where he ______ some European partners．
| A．would meet | B．is meeting |
| C．meets | D．had met |
_____ an important decision more on emotion than on reason, you will regret it sooner or later．
| A．Based | B．Basing | C．Base | D．To base |
John thinks it won't be long _____ he is ready for his new job．
| A．when | B．after | C．before | D．since |