4．build ________ 逐渐增强；建立；开发

　　5．lead ________ 导致；造成(后果)

　　6．________ addition 另外

　　7．focus ________ 集中(注意力、精力等)于

　　8．keep...free ________ 使......免受(影响、伤害

　　 等)；使......不含(有害物)

　　【答案】　1.of　2.to　3.off　4.up　5.to　6.in

　　7．on　8.from

　　根据提示补全下列教材原句

　　1．Recently，however，scientists ________________ that long­term use of these fertilizers can cause damage to the land and，even more dangerous，to people's health.

　　然而，最近，科学家发现长期使用这些肥料会造成土地受损，甚至更危险的是，会对人们的健康造成危害。

　　2．Crops such as peas or soybeans put important minerals back into the soil，________________ such as wheat or corn that need rich and fertile soil.

　　像豌豆或大豆这样的农作物将重要的矿物质带回土壤，从而使之适宜于要求土壤肥沃的农作物，比如小麦或玉米。

　　【答案】　1.have been finding　2.making it ready for crops

　　　阅读P14教材课文，选择最佳答案

　　1．What is the main idea of the fourth paragraph?

　　A．Long­term use of chemical fertilizers can cause damage to the land and people's health.

　　B．Problems caused by chemical fertilizers.

　　C．Farmers and customers turn to organic farming.

D．Other methods to keep the soil fertile.