a sum of 与a quantity of 区别
a sum of 释义：
一笔（修饰货币）
例句：
You owe a certain person a sum of money.
你欠着某人一笔钱。
a quantity of 释义：
一些
例句：
She carried a quantity of matches in an old apron, and she held a bundle of them in her hand.
她用一条旧围裙兜着许多火柴，手里也拿着一扎。
a sum of 释义：
一笔（修饰货币）
例句：
You owe a certain person a sum of money.
你欠着某人一笔钱。
a quantity of 释义：
一些
例句：
She carried a quantity of matches in an old apron, and she held a bundle of them in her hand.
她用一条旧围裙兜着许多火柴，手里也拿着一扎。