It seems that oil______from this pipe for some time.We’ll have to take the machine apart to put it right.
| A．had leaked | B．is leaking |
| C．leaked | D．has been leaking |
21. Perseverance is a kind of quality, and that’s ______ it takes to do anything well.
| A．what | B．that | C．which | D．why |
20. —Why was __ you lost all your keys？
—It was because of my carelessness.
| A．that | B．what | C．it that | D．One |
19. To work at home has been made _____ with the development of the Internet.
| A．it probable | B．it likely | C．likely | D．possible |
18. ------- Could you please tell me more about the city?
------- Sorry, I’m a newcomer. I know nothing else ______ you know now.
| A．except for | B．except | C．except what | D．Besides |
17. ________ is expected, according to the on-line survey, is that prices of houses will not go up any longer.
| A．It | B．As | C．Which | D．What |