扩展径的英文：
expansion paths

expansion是什么意思：
n. 扩大，膨胀；扩张物

It's the expansion of a river.
这是河流的延伸部分。

This is nothing but the binomial expansion.
这不过是二项展开式。

They have an expansive grassy play area.
他们有一片广阔的游乐草地。

They have played an expansive style of rugby.
他们采用向外展开打法打了一场橄榄球。

That was a vast expanse of grassland.
那曾是一片广阔的草原。

paths是什么意思：
n. 小路；路线；行动计划

The path of duty is the path of safety
尽职的路是安全的路

strike one's path
朝...方向进; 取道前进

A route or path across or over.
横向路横越或横跨的路线或道路

The path to glory is always rugged.
通向光荣的道路常常是坎坷不平的。

The path down to evil is easy.
人很容易堕入罪恶的道路。