Directions: Fill in the blamks according to Reading 2.1. a _________ concern 主要关注点2. __________ pollution 人为污染3. natural ____________ 自然污染4. come in ___________ with 接触5. on the _____________ 大体上，基本上6. be held ______________ for 被认为应对…负责7. ____________ the aquatic ecological system恢复水生态系统8. rest ____________ 尽管放心9. in the ___________ 同时10. _________out 找到（解答）；作出11. a ___________, long-term solution 可持续的长期的解决办法