The tendency of a body in motion to continue in motion along a straight line is known as inertia. 运动物体继续作直线运动的倾向叫惯性。
The simplest form of wave motion consists of the combination of a transverse simple harmonic vibration and a uniform translation. 波动的最简单形式是横向简谐振动和匀速直线运动的组合。