根据句意及首字母提示，补全句中所缺的单词。

1. Look at the s________ of an elephant. It's amazing.

2. We c________ with each other mostly by e-mail.

3. We can learn by e________ that oil and water will not mix.

4. He is f________ with Chinese ancient history.

5. At the entrance of the street there is a "No E ________" sign.

6. If you paid more a________ in class, you might actually learn something.

7. "Sit!" he said, and the dog o________ him instantly.

8. The truck s________ up going down the hill.

9. The difference between h________ and animals is that the former one can make tools but the latter

    one can't.

10. After supper his parents always go d________ to have a walk and Tom goes u________ to do his

      homework.