a kind of 用法?

题目

a kind of 用法?
a kind of apple 和 a kind of apples 哪个对 为什么?

答案

a kind of apple正确.a kind of ＋名词的单数.
a kind of ＋名词的单数;kinds of +名词的复数.例如：a kind of bird；kinds of birds
做主语是以kind的单复数来定,例如：
All kinds of birds are in the zoo.
There is a kind of bird in the zoo.