The fuel cells could be used as auxiliary power units to produce electricity when an aircraft is on the ground, for example, allowing its engines to be turned off.

燃料电池可以当做辅助供电单元使用，比如，当飞机在地面时，可以允许关闭飞机发动机。

youdao

Ground water is used as the cooling water source of heat pump units in summer a great deal of production sewage is used as extracted heat sink for units in winter.

夏季利用地下水作为水源热泵机组的冷却水，冬季利用该厂丰富的污水作为机组的吸热源。

youdao

The project brings together 90 housing units on six upper floors, and a home for young autistic workers on the ground floor.

该项目在顶部的六层汇集了90套住房，一层是一个患有自闭症的青年工人之家。

youdao

The package-delivery company said it will increase its shipping rates for its FedEx Ground and FedEx Home Delivery units by an average of 4.9%, effective Jan. 2.

WSJ: Stocks Off Highs After Report on EU Ratings

For affected units, the Air Force says it will shift its focus to ground training.

NPR: Federal Budget Cuts Ground Air Force Aircraft

Research units such as its recently created Institute for Frontier Medicine regularly break new ground.

CNN: ASIANOW | The Asiaweek Best Universities 1999 | The Rankings | #2 Kyoto University