—My cousin is very clever but he doesn't work hard at his lessons.—________.

Scientists say it may be five or six years ______  it is possible to test this medicine on human patients.

---Do you need any help,Lucy? ----Yes．The job is _____I could do myself ．

I would appreciate ________ much if you could write to me as soon as possible.

There is no doubt _____ China has made rapid progress in space exploration.