将“underground"翻译成中文

Also provided is an underground coal gasification method.

该煤炭地下气化炉消除现有技术气化生产阶段中贯通速度慢、结构不稳定的缺陷。

London is such a large city that visitors must use buses and the underground railway to get about.

伦敦是个大城市,游客必须乘公交或地铁才能出行。

In the London underground there is a warning to "mind the gap" when boarding the train.

在倫敦地鐵,上車時會有「注意間隙」提醒。