The theory he sticks to ______ to be of no use in our studies.
| A．proves | B．prove |
| C．proving | D．be proved |
I think this is the very work that we must finish ____ her.
| A．to help | B．help |
| C．helping | D．helped |
. ______ smoking, he would not have got cancer in the lung.
| A．Was he given up | B．Had he given up |
| C．Did he give | D．If he gave up |
I was too careless.If only I ___ my car!
| A．hadn't lost | B．would not have lost | C．didn't lose | D．haven’t lost |
He was disappointed that his plan did not ___.
| A．go on | B．go off | C．go through | D．go out |