级数的和的英文：
sum of series

sum是什么意思：
n. 总数，总和；算数；金额；要点
v. 合计；总结

There are spots in (or on) the sum
人孰无过

This is the sum of this book.
这就是这本书的要点。

A Lump Sum Rate of ...
费用合计…

The sum of a column of figures.
总额一列数字的总和

He paid an enormous sum.
他支付了一大笔款项。

series是什么意思：
n. 系列，连续；系列节目；系列比赛；丛书；串联；级数

There was a series of explosions.
有一连串的爆炸事件。

A series of tilting matches; a tournament.
比武一系列持矛的比武；马上比武

A series of accidents disordered the shop.
一连串的意外事件把店里弄得乱七八糟。

He guested on a television series.
他客串了一个电视系列剧。

a graduated series of textbooks
分等级的教科书系列