What kind of...是问...是哪一类的,或...是什么样(性格,属性等)的.of 后面可以是单数也可以是复数.
如:What kind of your English teacher?你的英语老师是个怎样的人?
He is very serious teacher.他是个很严肃的老师.
What kind of these cakes?这些蛋糕是哪一种蛋糕.
They are made by wheat.它们是小麦做的.
kinds of 和上面的不同.
如:How many kinds of books are there.有多少种类的书.这里kinds就是做kind的复数.
而:There are kinds of books here.这里有很多种书.这里kinds of 就相当于many of,大量的.