Engineers on the ground designed a way the astronauts could connect air-cleaning devices from the command module to the air system in the lunar module.

VOA: special.2009.07.22

The Earth seems to be a pretty good inertial system, because on the ground, you leave something, it stays there.

地球看上去是个不错的惯性系,因为什么东西放在地上,都会保持静止

耶鲁公开课 - 基础物理课程节选

The Obama administration's plan will replace Bush's anti-missile plan with a re-designed sea- and ground-based system, which destroys short and mid-range missiles instead of intercontinental missiles.

VOA: standard.2009.09.24

He says this is one reason he recommended scrapping plans to build a sophisticated radar system in the Czech Republic and installing ground-based interceptors in Poland.

VOA: standard.2009.09.17

During an appearance on the NBC television program Meet the Press, Specter said he would also like to see the president reach beyond the federal court system - the traditional training ground for members of the high court.

VOA: standard.2009.05.03