He lifted the stone only _______ it dropped on his own feet.
| A．have | B．had | C．having | D．to have |
Today, when scientists examine mummies, they wear special clothing for protection _____ they breathe in harmful gas.
| A．even though | B．in case | C．until | D．unless |
Wow! That’s Uncle Sam. Now he’s in Paris, _____ he?
| A．isn’t | B．hasn’t | C．doesn’t | D．wasn’t |
When _____ what is most important in life, some choose money, ____ others choose friendship.
| A．to decide; and | B．to decide; because |
| C．deciding; / | D．deciding; while |
—Why haven’t you asked her to come here?
— She _____ an important experiment when I found her and she _____ it.
| A．had done; didn’t finish |
| B．was doing; hasn’t finished |
| C．did; wouldn’t finish |
| D．has done; hadn’t finished |
It was when we were returning home _____ I realized what a good feeling it was to have helped someone in trouble.
| A．which | B．that | C．where | D．how |