那怎样才能降低转速呢？

So how do you reduce your rev rate?

youdao

齿数不同的一对齿轮能够提高或降低转速。

A pair of gears with different number of teeth will increase or decrease the speed of rotation.

youdao

要降低噪音，最简单的方法是增大旋翼桨叶的夹角，也叫“节距”，或是降低转速。

The simplest way to dampen a helicopter's noise is to increase the Angle of the rotor's blades, also called the pitch, and slow them down.

youdao