--Do you often hear John ___ in his room? --Yes. Listen! Now we can hear him ___ in his room.
| A．sing; to sing | B．singing; singing | C．sing; singing | D．to sing; singing |
In the last few years thousands of films all over the word.
A .have produced B. have been produced
C. are producing D. are being produced
I'll go to the library as soon as I finish what I .
| A．was doing | B．am doing | C．have done | D．had been doing |
Tomin the library every night over the last three months.
| A．works | B．worked |
| C．have been working | D．had been working |
—Bob has gone to California.
—Oh, can you tell me when he ?
| A．has left | B．left | C．is leaving | D．would leave |
You ____ television. Why not do something more active?
| A． always watch | B． are always watching |
| C． have always watched | D． have always been watching |