1. prevalent: existing very commonly or happening often 流行的;普遍的
2. prototype: the first example of something 原型
Eg. Pilots have begun testing a prototype of the new aircraft.
3. intervention: the practice of refusing to get involved in a situation 介入;干涉
Eg. It can operate without human intervention.
4. far-fetched: extremely unlikely to be true or to happen 牽強的;難以置信的
Eg. At the time, his ideas were considered far-fetched.
5. vacuum: a space that is completely empty of all gas 真空
Eg. The whole apparatus operates under high vacuum.