6. A. land B. world C. water D. mountain

5. A. smaller B. fewer C. more D. less

4. A. Look after B. See C. Watch D. Look at

3. A. another B. other C. the other D. others

2. A. in B. at C. on D. over

1. A. know B. say C. hope D. wish

10.D. 根据所给词的词义可知答案。

　(3)

　What do we know about the sea? We (1)______ that it looks very beautiful when the sun is shining (2)______ it. We also learn that it can be very terrible when there is a strong wind. What (3)_____ things do we know about it?

　The first thing to remember is that the sea is very big. (4)_____ the map of the world, there is (5)______ sea than land. The sea covers three quarters of the (6)______.

　Some parts of the sea (7)______ very shallow. But some places are very deep. There is one place near Japan. It is nearly 11 kilometers deep. The (8)____ mountain in the world is about 9 kilometers high. If we put the mountain into the sea at that place, there would be (9)______ kilometers of water above it!

　The sea is salty. There is one sea called the Dead Sea. It is very salty. It is (10)_____ salty that swimmers cannot sink! Fish cannot live in the Dead Sea.

9.C. 声音应该是听到的。

8.D. 根据上下句和四个疑问词的意思可知答案。

7.A. 这里应该是老师在science class 上问学生问题。