He was a courier for the Polish underground and parachuted into Warsaw.

他是波兰地下组织的信使，被空降到了华沙。

《柯林斯英汉双解大词典》

Scientists who want to mitigate carbon dioxide’s effects on global climate have started experimenting with storing the gas underground a process known as carbon sequestration.

为了减轻二氧化碳给全球气候带来的影响，科学家们已经开始尝试将其储存于地下，又称之为碳吸收。

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The train was trapped underground by a fire.

列车被一场大火困在了地下。

《柯林斯英汉双解大词典》

Black cohosh is an herb that comes from the root or underground stems of a tall plant in the buttercup family.

VOA: special.2009.05.19

What we don't get here is a sense of whether there really is an alternate secret postal system that serves a sort of underground of private networks.

在这里我们所不明白的是，是否真的存在一个,提供地下的,私密的通信服务的，秘密邮政系统。

耶鲁公开课 - 1945年后的美国小说课程节选

You know, there's been a lot of argument with the underground, for example.

比如，关于地铁的问题一直有很多争议。

伦敦的现代化 - SpeakingMax英语口语达人

In 2012, the transport minister approved tunnelling underground a section of the A10 ring road that bisects Zuidas and there are also plans to enlarge and improve the Amsterdam Zuid train station, both to begin construction by 2015.

BBC: Living in: Amsterdam

It was a facility built deep underground in a hillside.

CNN: Starr: Libya has scientific expertise on WMD

Someone who knows all too well what Ethan may go through is Katie Beers, who as a 10-year-old was held underground in a concrete bunker for two weeks by a New York man.

CNN: FBI: Bombs found in Alabama kidnapper's bunker