1、只能修飾可數名詞的：a large/ great/ good number of, a good/ great many, dozens of, scores of, quite a few。
2、只能修飾不可數名詞的：a great deal of, a large amount of, quite a little,a large sum of。
3、既可修飾可數也可修飾不可數名詞的：plenty of, a lot of, lots of, a large quantity of, a good supply of。
4、但是a number of不能修飾不可數名詞。
