外经的英文：
superficial channels

He has a superficial knowledge of a subject.
他对一门学科略知皮毛。

This is only superficial prosperity.
这只是表面繁荣。

A superficial injury is not serious.
表皮的伤不太严重。

Giving a momentary or superficial impression of brilliance.
闪烁的，炫耀的给人以短暂或表面印象的光彩或才华的

And it's a superficial, formal, external similarity.
这只是一种浮于表面的相似。

There are at present three television channels.
目前有三个电视频道。

The river channel is deepening.
河床正在加深。

Keep the drainage channel clear.
保持下水道畅通。

The sewage channel chokes.
这条污水道塞住了。

They channeled their cotton field.
他们在棉田里挖了水渠。