（A）根据句意和汉语注释，写出单词的正确形式：
1. Liu Tao is the ___________ boy in his class, he needs more exercise.(瘦的)
2. Look! The boy is playing with two white ______________ (老鼠)
3. I don’t like the ________________ (广告) because they are too boring.
4. I think it ______________ (必要的) to give it clean water to drink.
5. Uncle Tom is a very kind man. He often helps people __________ (解决) problems.
6. You can put some stones at the ___________ (底部) of the tank to make it more beautiful.
7. Do you really ____________ (相信) what he said a moment ago?
