3．_________

3．Nowadays many young girls eat very little food in order to lose w　.

2．_________

2．Smoking is a very u　 habit which smokers should give up .

1．_________

根据下列句子的句意及所给单词的首字母，在句子右边的横线上，写出空缺处各单词的正确形式。

1．Western diet c　too much fat and sugar in the from of potato chips , butter , cream , coca cola , cream and chocolate .

20．_______ an atom is broken up , it may _______ another atom to break , too .

A．When ; cause　　　　 B．As ; make

C．While ; cause　　　　 D．Since ; cause

19．______ people in other countries in the world were trying to catch wild animals and birds and were still collecting seeds and nuts , farmers in China were already developping the science of agriculture .

A．When　　 B．As　　　 C．While　　D．Since

18．Many fruits are ________ Vitamin(维他命)C .

A．rich with　 B．rich for　　C．rich on　　 D．rich in

17．______ the continuous heavy rain for about two days , rivers have all risen and floods may happen at any time .

A．Because　　B．With　　C．As to　　D．On account of