重点讲解：
1. clean up 清理，清除（污染物）；
例句：We should clean up the dirty parts of the sea.
我们应该清除海里的污染部分。
2. a clean bill of health 身体状况良好；
例句：President Mitterrand, 75, has been given a clean bill of health by doctors in Paris.
巴黎的医生们告诉75岁的密特朗总统，他的身体非常健康。
3. take the lead 领先， 带头；
例句：They took the lead in conducting the experiments.
他们带头做试验。
4. thanks to 幸亏；归因于；
例句：Thanks to that job I became an avid reader.
多亏了那份工作我才成了一个喜欢阅读的人。
5. benefit from 获益；对…有益；有利于；
例句：A stammering child can benefit from speech therapy.
口吃的孩子可以从言语矫治中获益。
6. be attributable to 可归因于…的，可归结于…的；
例句：10,000 deaths a year from chronic lung disease are attributable to smoking.
吸烟导致每年有1万人死于慢性肺病。
7. grapple with 努力解决（问题）；设法克服（困难）；
例句：The economy is just one of several critical problems the country is grappling with.
经济问题只是该国正竭力解决的几个关键问题之一。
8. lag behind 落后；赶不上；
例句：The restructuring of the pattern of consumption in Britain also lagged behind.
在消费结构重组方面，英国也落后于人。
