Question

How many ________ medicine are used for the children of six years old?

1. A.
   three kinds
2. B.
   kinds of
3. C.
   kind of
4. D.
   some kinds

Answer 1

B
解析：很显然，用how many提问就不能选A、D两个答案。kind of意为“有点”，与题意不符。kinds of表示“种类”。