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.
