8. 强调 9 .总结 10. 营养

　　　11. 在过去的半个世纪 12.加大，增强

　　　13.导致 14.集中于 15.使......免受（影响，伤害）

16.对......造成伤害 17. 冲掉，冲洗

18.转向，求助于 1 9.每隔几年

20.充满，装满

　五．课前导入

请同学们思考：

　　What is the safety and importance of eating "green food"?

　六．阅读文章回答问题

　　1．Why are chemical fertilizers so popular in farming today?

　　2．What problems can be caused by using chemical fertilizers?

　　3．What is organic farming?

　　4．What is the main reason for using organic farming methods?

　七．知识梳理（重点单词和短语）

　　1．reduce v. 减少, 降低

　　公司尽力通过减少花销来提高利润。

　　The company tries to increase profits by reducing costs.

　　 [即学即练1] We expenses this year. 今年我们已经减少了业务开支。

　　2．lead to 意为导致、造成(后果)，后多跟名词、代词或动名词。

　　All roads lead to Rome. 条条大道通罗马。

　　[即学即练2] Too much work and too little rest often illness.

　　　　　　　过量的工作和过少的休息会引起疾病。

　　比较：result in引起，导致(某种结果)、使获得(某种成果)、结果......。

　　result from由......造成、因......而产生。

　　The accident resulted in two deaths. 事故导致两人死亡。

　　[即学即练3] Sickness sometimes eating too much.

疾病有时是由吃太多引起的。

　　3．focus on 集中(注意力, 精力等)于...，常形成 focus one's attention on sth.

　　You should focus your attention on your work. 你应该把注意力集中在你的工作上。

　　[即学即练4]

　　【句子仿写】 我今天太累了，无法集中精力做任何事。

　　4．keep... free from /of... 使......免受(影响, 伤害等); 使不含(有害物)

We put our books in bookcase to keep them free from dust.

为了不让书受灰尘污染，我们把它们放在书柜里。

　　[拓展]

1) keep ... from... "隐瞒, 不把......告诉(某人), 阻止, 避免" 如：

He won't be able to keep the truth from his father. 他无法向父亲隐瞒真相。

You can't keep him from doing that thing. 你不能阻止他做这件事。

比较：keep sb./sth. from doing sth./being done

stop sb./sth. from doing sth. /being done

prevent sb./sth. from doing sth./being done