Gun control is a subject ___________ Americans have argued for a long time.
| A．of which |
| B．with which |
| C．about which |
| D．into which |
He ___________ unwisely, but he was at least trying to do something helpful.
| A．may have acted | B．must have acted |
| C．should have acted | D．would act |
Having checked the doors were closed and ______ all the lights were off, the boy opened the door to his bedroom.
| A．why | B．that | C．when | D．where |
______ is often the case is that Tom doesn’t study hard and fails in passing an exam.
| A．That | B．What | C．It | D．As |
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 |
Last Sunday a few of us arranged to meet in town, but Jenny didn’t _______.
| A．give up | B．make up | C．turn up | D．take up |