界线的英文：
limits
bounds
dividing line

参考例句：

There are no indecisive boundaries between the two opinions.
这两种意见界线分明。

a remote outpost of civilization
遥远的文明界线

a chaste border of conventionalized flowers.
一种界线简单的格式化语言。

Being without boundaries or limits; infinite.
无限制的没有限制或界线的;无限的

The dividing line is not always so clear.
这个界线并不总是那么清楚的。

As a rule this concerns only part of the whole terminator
通常这只是影响地界线的一部分。

The boundaries are clearly marked off on the map.
界线清清楚楚地在地图上标了出来。

I don't understand why the knee is a barrier.
我不理解为什么非得以膝盖为界线。

The two neighbors disagreed bitterly about their boundary line.
这两个邻居在住房界线问题上剧烈争吵。

The thing that masked her as having passed the line was that she no longer had reticences before her husband
她超过年龄界线的标志是她在丈夫面前不再忸怩。

limits是什么意思：
n. 限制；限量，限度；界线
v. 限制；限定

Life is limited, but there is no limit to learning.
生命是有限的，但学问是无限的。

He is a man of limited scope.
他是一个见地狭窄的人。

limit of maximum financial revenue
财政收入最大限量

bounds是什么意思：
n. [bound] 的复数形式；界限，跳动
v. [bound] 的第三人称单数形式；跳跃；弹回；邻接

Where are you bound for?
君将何之？

The persons bound by such a contract.
合伙人受此种契约限制的人

Keep it within bounds.
请把它保持在限制范围内。

dividing是什么意思：
adj. 区分的，分划的

Dichotomous:Divided or dividing into two parts or classifications.
两分的:被划分或划分成两部分或类群的.

Four divides eight.
4能除尽8。

We divided up the money.
我们把钱分了。