In the past few years, great changes in Chongqing.
| A．have taken place | B．took place |
| C．have been taken place | D．have happened |
Our parents often tell us ___________ on the street.
| A．not play football | B．to not play football |
| C．not to play football | D．not playing football |
— We’d better go home right now. The sky is getting .
— Okay, let’s go!
| A．blue | B．clear | C．grey | D．bright |
While I _____________, someone ___________at the door.
| A．did my homework; knocked |
| B．do my homework; knocks |
| C．was doing my homework; knocked |
| D．was doing my homework; knocks |
They ____________ in the river when it __________ to rain.
| A．were swimming; began |
| B．swam; was beginning |
| C．swam; began |
| D．were swimming; was beginning |
Please knock at the door ________ you come into the room.
| A．before | B．after | C．until | D．while |