a good/great many

1. 很多
   There are a good many people in the hall.

   大厅里有很多人。

as many as

1. 和……一样多
   You may take as many as you want.

   你要多少就可拿多少。

many a

1. 许多的
   We've been here many a time.

   我们这儿已来过多次。

• a good (or great) many
  a large number.
• many a ——
  a large number of.