按要求完成句子

1. 我从未读过这么好的书.

    I _____ _____ _____ such a good book.

2. I have fed the cat already.(改为一般疑问句)

    _____ you _____ the cat _____?

3. He has cleaned out the refrigerator already(改为否定句)

    He _____ _____ _____ the refrigerator yet.

4.We have been friends for 3 years.(对划线部分提问)

    _____ _____ _____ you _____ friends?

水体污染、水体污染物、水体污染源概念及区分