Although the causes of cancer_____, we do not yet have any practical way to prevent it.
| A．are being uncovered | B．have been uncovering |
| C．are uncovering | D．have uncovered |
The day he had been looking forward to _______ at last.
| A．come | B．coming | C．came | D．has come |
Great changes __________ in this city over the past five years.
| A．took place | B．have been taken place |
| C．were taken place | D．have taken place |
My uncle _____ to see me. He’ll be here soon.
| A．comes | B．is coming | C．had come | D．came |
Tim ____since he lost his job three weeks ago.
| A．had been unemployed | B．was unemployed |
| C．has been unemployed | D．has unemployed |
Mother wanted to be a good provider, a role she _______ since her marriage to Father.
| A．shoulders | B．has been shouldering |
| C．is shouldering | D．shouldered |
--- Now where was I ?
--- You ______ me about your travels in Canada.
| A．told | B．were telling |
| C．have told | D．will tell |
I intend to buy this kind of pen because I the pen well.
| A．have told, writes | B．have been told, writes |
| C．was told, wrote | D．have been told, is written |
-----Did Alan enjoy seeing his old friends yesterday?
----- Yes, he did. He _____ his old friends for a long time.
| A．hadn’t seen | B．didn’t see |
| C．hasn’t seen | D．wouldn’t see |
---Why did you leave that position?
---I a better position at IBM.
| A．offer | B．offered | C．am offered | D．was offered |