You know this is the third rail, right?

你知道这是第三根铁轨对吧？

Third rail current collection comes in a variety of designs.

第三轨受流可以设计成不同形式。

The diagram above shows a top contact third rail system but there are other types as shown in this diagram.

下图展示了上触式及其它类型的第三轨供电系统。

In some cities, a third rail provides power to a subway train, usually operating underground; electricity passes through the rail.

在一些城市，第三道铁轨(电动机车的输电轨)给通常在地下运行的地铁列车供电，电力通过这道铁轨传输。

That is a slightly lower proportion than in Greece or Sweden, but far higher than in America, where raising fuel taxes is nonetheless said to be a "third rail", deadly to politicians.

比希腊和瑞典低一些，但是远远的高于美国。在美国，提高燃油税就像是第三铁道，对于政客来说是致命的。