1、many、a great/good many?、a great/large number of?、scores of、dozens of和?(quite) a few,?這類“許多”修飾作主語的名詞時，只能修飾名詞復數形式，謂語動詞用復數。
There are a great/good many English books in our school library.
2、the number of + n?（可數名詞復數）?表示"....的數目”,用它做主語時，謂語用單數
The number of the students in our class is 55.
3、既可以修飾可數名詞復數，?又可以修飾不可數名詞a lot of?、lots of?、plenty of?、supplies of?，a great/quantity of?、great/large quantities of。
He has got a lot/lots of questions to ask.
4、只能修飾不可數名詞的“許多”?有：much、a great / good deal of?和a large amount of?，這類“許多”修飾主語名詞時候，?謂語用單數。
I don't know they gave us much help.
5、a great deal?做名詞詞組和副詞詞組，也表示“大量，許多”，還可以修飾比較級，表示程度。
At the end of the year there was a great deal to do.年底有很多事情做。
6、many a /an +?單數可數名詞也表示許多，這個短語作主語時謂語用單數。
Many a girl in our class has learned to swim.