—How many students are there in the classroom?—. They are all in the lab.A. SomeB. NoneC.

问题补充：

—How many students are there in the classroom?

—. They are all in the lab.

A. Some

B. None

C. All

D. Neither

答案：

A. Some

(答案→)B. None

C. All

D. Neither

解析：Some一些；None一个也没有；All所有都；Neither两者都不；句意：教室里面有多少学生？根据下文，他们都在实验室里面。可知前文指的是，一个也没有。故选B。