题目内容
12．-Which of the twin sisters is a doctor？-______ are．（ ）| A． | All | B． | Both | C． | Either | D． | Neither |
分析 --这双胞胎姐妹中哪一个是医生？两个都是．
解答 答案：B．all意思是"三者或三者以上都"作主语时，谓语动词要用复数；both意思是"两者都"作主语时，谓语动词要用复数；either意思是"两者之中的任何一个"；neither意思是"两者都不"作主语时，谓语动词要用单数．根据"the twin sisters"可知要从两者之中进行选择，又根据"____ are．"所以要用both，故选B．
点评 首先要掌握这几个不定代词的意思以及用法，然后结合具体的语句，就可以确定正确答案．
练习册系列答案
相关题目
3．The newspaper says if more underground lines next year，it will be much easier for people to travel around Nanjing．（ ）
| A． | will be finished | B． | have finished | ||
| C． | are finishing | D． | are finished |