Vertical farms use hydroponics and aeroponics, soil-free growing techniques once researched by NASA to grow plants in space.

纵向农场使用水耕法和空气种植法，NASA曾经研究无土栽培技术用与在太空中培育植物。

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In order to attract more people, a growing number of museums are free for the public.

为了吸引更多的人，越来越多的博物馆对公众免费开放。

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Knowledge is free on the Internet at a small but growing number of colleges and universities.

在一些高校的网站上，有免费的知识，这些高校为数不多，数量却一直在增加。

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There is a growing market for products that are gluten-free.

VOA: special.2010.11.16

"That is why last growing season, we took most of our produce to schools in this community and distributed it for free."

VOA: standard.2010.03.10

Waste-free is a growing trend both among consumers and also in the business world.

FORBES: 52% of GM facilities are landfill-free

The Europeans, who want to break free from their growing dependence on Russian energy supplies, desperately need supplies from the region to make the Nabucco pipeline viable.

BBC: Struggle for Central Asian energy riches

Free markets are growing spreading individual opportunity and national well-being.

CNN: Text Of Clinton's Remarks To The United Nations