3.　　 科学家们已经在宇宙中发现了许多别的星系。

Scientists ______　 _______　 _______ many other ______ in the _______.

2.　　 我们还没有在其他行星上发现生命。

We haven’t ______ 　_______ on other ______ in the ______.

1.　　 科学家们认为世界上存有生命已有几百万年的历史了。

Scientists _____　 ______ there has been life _____　 _____ for ______　 ______ years.

6. anywhere　 7. Have　 8. for　 9. is　 10. Thank　 11. be　 12. again

4. What; up to　　 5. remember to ; back to

A: Mum, I’ve lost my art book. Have you _______ it anywhere?

B: Is it the book ______ a red cover?

A: Yes, that’s ______! Where did you _______it?

B: Sorry, I ______ seen it ______.　 _______　 _______ you tried to look______it under your bed? Maybe you dropped it there.

A: Oh! Here it ______.　 ________ goodness!

B: You should ______ more careful from now on.

A: Yes, it won’t happen _______.

单元练习答案

5. ----Have you heard the news ______?

　 ----No, not ______.

A. already ; already　 B. yet ; already　 C. yet ; yet　 D. recently ; already

4. Please remember _______ to Beijing ______ business ______ plane.

A. go ; on ; by　 B. to go ; by ; in　 C. to go ; on ; by　 D. go ; on ; in

3. “_____ does it take?” “It takes half an hour.”

A. How long　 B. How soon　 C. How far　 D. How often

2. My father had to work ______ Sunday morning.

A. in　 B. to　 C. on　 D. at