In America, if__________friend has invited you to drop by anytime, it is__________best to call before visiting to make sure it is convenient for him.
| A．a; a | B．a; 不填 | C．the; a | D．the; 不填 |
Be careful when you cross this very busy street. If not, you may _____ run over by a car.
| A．have | B．get | C．become | D．turn |
My teacher _____ me the key to the classroom but I’m afraid I _____ it.
| A．had given, lost | B．has given, lost | C．gave, have lost | D．has given, have lost |
---John and Tom, you two clean the classroom today, _____?
---But we cleaned it yesterday.
| A．do you | B．will you | C．didn’t you | D．don’t you |
Pleasant as they made it ______ in Jiuzhaogou, we felt tired after the long journey.
| A．to travel | B．travel | C．travelled | D．travelling |
Although the police thought he was the most likely one, _____ they had no exact proof about it, they could not arrest him.
| A．when | B．until | C．before | D．since |