---The window is dirty.
----I know. It ______ for weeks.
| A．hasn’t cleaned | B．didn’t clean |
| C．wasn’t cleaned | D．hasn’t been cleaned |
He was very busy yesterday, otherwise he ____ to the meeting.
| A．would come | B．came | C．would have come | D．had come |
Sometimes our opinions differ _________ what we choose to observe and how we deal with what we’ve observed
| A．which | B．since | C．because | D．because of |
– Will you please go to see the movie Guanyinshan with me?
– No, I won’t. I it already.
A. saw B. have seen C. see
________ people were hurt in the accident.
| A．Hundred of | B．Hundred |
| C．Hundreds | D．Thousands of |
Gun control is a subject ______ Americans have argued for a long time.
| A．of which | B．with which | C．about which | D．into which |