两者的区别是：
many a+单数可数名词：形式上为单数，但意义上为复数
a good many后加可数名词复数，和many 的用法差不多
释义：
many a：许多的
a good many：许多，很多
近义词：
the great promises of 具体... ...
a good deal of 大量(的)，许多(的)
a good many 许多，大量
a great deal of 大量(的)
短语词组：
How many days a
多少天一次
Many With A Balcony
很多都带有凉台
many a
许多的
a good many
许多
a great good many of
至关多
a good many people
很多人
造句：many a
Many a glad day has come in my life, and I have laughed with merrymakers on festival nights.
我生平有过许多快乐的日子,在节日盛典的夜晚,我曾经与狂欢者一同大笑.
This paper lantern with the infamous swastika sign on it was doubtless a feature in many ahome.
这只纸灯笼上有臭名昭著的纳粹标志，无疑当时许多人家都有这种灯笼。
First, for many a day it rained, thus the team marked time.
首先，许多天，天都一直下雨，这导致了队伍停止不前。
造句：a good many
A good many today is better than yesterday and tomorrow, not good.
一个美好的今天更胜过许多个没好的昨天和明天。
There is an active Society which brings to book a good many parents who starve and tortureand overwork their children, and intimidates a good many more.
一个很积极的社会记录了许多父母是怎样让自己的孩子忍饥挨饿，折磨他们，让他们过度工作，对他们愈加 恐吓的。
I've seen a good many little girls in my time, but never ONE with such a neck as that!
鸽子十分轻蔑地说，“我这辈子看见过许多小姑娘，可从来没有一个长着像你这样的长脖子的！