Be careful with such things. If you , you’ll drop them.
| A．don’t | B．won’t | C．aren’t | D．do |
31. Hillary Clinton arrived in Beijing yesterday, ______ the start of her short visit to China.
| A．marked | B．having marked | C．marking | D．to mark |
30·You can make a complaint to the local government____ you are happy with the way things are.
| A．unless | B．if | C．once | D．As |
29. ---- I wonder ______ Mr. Black changed his mind to take part in the movement.
---- After he listened to the speech by Mr. King.
| A．when was that it | B．when was it that | C．when that was | D．when it was that |
28. We finally managed to make the customers ______ of the quality of the vehicle.
| A．to convince | B．convincing | C．convince | D．Convinced |
27. ---- Mr. Wang got the first prize in the singing competition last week.
---- Oh. That’s what he ______ for years.
| A．had been expecting | B．has expected | C．expected | D．has been expecting |