电工正在安装一个金属耦合器来连接这两根电缆。

The electrician is installing a metal ___coupler to join these two cables.

这位音乐家用耦合器将电子琴和管风琴连接起来，进行二重奏表演。

The musician used a ___coupler to connect the electric keyboard with the pipe organ for a duet performance.

这种化学物质作为偶联剂帮助两种不同分子结合。

This chemical acts as a ___coupler to join two different molecules together.