There are three girls in the library.在three girls这里划线提问,

问题描述:

There are three girls in the library.在three girls这里划线提问,

How many girls are there in the library

Who are there in the library?

正确答案:Who is in the library?
对three提问,才是用how many girls引导问句;
用who提问时,其后的单词一律用单数形式,不能用复数形式.