relay

vt. 中继(用继电器控制,接替)
n. 继电器(转播,备用品,替班人)

Scientists have set up two kinds of relay stations. One kind is on the earth, the other is a satellite placed in space around the earth.

科学家们已建立了两种中继站，一种在地球上，而另一种是放在地球周围太空中的卫星上。

The moving part of an electromagnetic device such as a relay, buzzer, or loudspeaker.

电枢电磁装置的移动部分，如继电器，蜂音器或扬声器