级数的英文：
progression
series

参考例句：

Harmonic proportion and progression are the essence of the created universe.
调和比例和级数是创造宇宙的本质。

The eighteenth century mathematicians used series indiscriminately
十八世纪数学家们不加辩加地使用级数。

The time may be computed to any desired degree of precision by taking enough terms in the infinite series.
在无穷级数中，取足够多的项，周期的数值可计算到任意的精确度。

macarthur surmised that competition equations should be considered as first elements of a Taylor series
麦克阿瑟推测，竟争方程应被看作为泰勒级数的首要元素。

The Taylor series here actually proved more accurate than I expected.
这里使用泰勒级数得到的结果实际上比我想像的要精确。

Shore hardness: Scale of hardness for resilient materials such as offset blanket or flexographic printing plate
这个尺度，分140等级。一个有着极硬尖端的锤子，从一固定高度降落，当它击中物料时，反弹的级数越高，物料越硬。

progression是什么意思：
n. 进展，发展；一系列，连续；级数

progressive tense
ph.1. 【语】进行时态,进行式

innovative progress
开拓进展

The road construction work is in progress.
筑路工程正在进行中。

Discontent is the first step in progress.
不满足是进步的第一步。

This is a progressive course in English study.
这是英语学习的渐进课程。

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