Unit13SectionA第五题答案
Unit13SectionA第六题答案
Unit13SectionA Grammar Focus第一题答案
1. We're trying to save the earth.
2. The river used to be so clean.
3. The air is badly polluted.
4. No scientific studies have shown that shark fins are good for health. .
5. We should help save the sharks.
Unit13SectionA Grammar Focus第二题答案
Unit13SectionA Grammar Focus第三题答案