Scientists say it may be five or six years __________it is possible to test this medicine on human patients.
| A．since | B．after | C．before | D．when |
---- Do you surf the Internet a lot？
---- Well,_______, I’m too busy with work to surf the Net.
| A．all right | B．I have no idea | C．at last | D．to tell you the truth |
with so much homework to do，David told his sister_____so much noise.
| A．to make not | B．not to make | C．not making | D．making not |
it was because of his kind nature _______I fell in love with Peter.
| A．before | B．when | C．that | D．since |
Kate is really young for the job, but, on the other _____, she is well trained.
| A．way | B．situation | C．chance | D．hand |
He couldn’t take part in the final exam _______ his serious illness.
| A．because | B．lead to | C．because of | D．when |