many的比较级是more；最高级是most。many可用作形容词，表示许多的，用作形容词时后接复数名词,表示许多同样的人或物(但数目不明确)。用作名词时，表示许多，许多人。用作代词时表示许多的人或物。
many和much的用法
(1)many修饰复数可数名词，表许多; much修饰不可数名词，表量或程度。
He has many friends, but few true ones.
There hasn’t been much good weather recently.
(2)many a: many a和many同义，但语气比较强，并且要与单数名词及单数形动词连用。
Many a prisoner1 has been set free. (=Many prisoners2 have been set free.)
(3)as many和so many均等同于the same number of。 前有as, like时, 只能用so many。
These are not all the books I have. These are as many more upstairs.
They worked like so many ants.
(4)as much等同于the same amount of，表同量和同一事情。
He bought two pounds of sugar and as much tea. 〔同量)
I was not in the least surprised, for I had fully3 expected as much. 〔同一事情)
(5)many和much之后不接名词时，作为代名词;另外much也可用副词。
Many of them were very tired.
I don’t eat much for lunch. 〔代名词)
He is much taller than I. (副词〕
扩展：表示“许多”的词组的对比分析
(1) plenty of, a lot of, lots of均表“许多”，修饰复数可数名词或不可数名词。
The room contained plenty of (or a lot of or lots of) students.(复数名词)
The room contained plenty of (or a lot of or lots of) furniture.(不可数名词)
(2) a great (or a good) deal of, a large (or a small) quantity of, a large (or a small) amount of, 均表(量)， 修饰不可数名词。
The room contained a great deal of furniture. (不可数名词)
The room contained a good deal of furniture. (不可数名词)
The room contained a large quantity of furniture. (不可数名词)
The room contained a large amount of furniture. (不可数名词)
The room contained a small quantity of furniture. (不可数名词)
The room contained a small amount of furniture. (不可数名词)
(3) a number of “许多;一些”;a great (large, good) number of “许多”，修饰复数可数名词，并且要与复数动词连用。
A number of books are missing1 from the library.
The number of books from the library is large.
The room contained a great (or large or good) number of students.(复数可数名词)
