the number of the books in our school library --- growing larger and larger

问题描述:

the number of the books in our school library --- growing larger and larger
a\ are
b\ is
c\ has
d\ have
为什么答案是b
理由越详细越好,好的有赏

the number of 后谓语动词用单数
它的意思是什么什么的数量
书虽然很多 但这是书的数量