工程师们正使飞机的发动机高速运转。

The engineers were running up the engine of the plane.

youdao

也就是说，在发动机高速运转时，这样的动作每秒钟要发生300次。

That is, there will be as many as 300 of these events every second that the engine is running at high speed.

youdao

工程师们正在高速运转发动机来检测飞机是否能立即飞行。

The engineers are running up the engine to see if the plane is ready to fly.

youdao