英语语法分析

I am concerned about the bars welded across the couplers.

我担心的是焊在连接器上的横栏。

Directional Couplers are four-port networks and fairly difficult to design.

定向耦合器是四端口网络，直接设计十分困难。

An inconvenience of prism couplers is that the prism material must have a high refractive index.

棱镜耦合器的一个不方便的地方是棱镜材料必须有较高的折射率。