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。
A body at rest remains at rest and a body in motion continues to move at a constant speed in a straight line unless acted upon by an external force. 除非受外力作用，否则静止物体将保持静止，运动的物体将继续作匀速直线运动。
A body at rest remains at rest, and a body in motion moves with uniform speed in a straight line, unless a force acts on it. 如无外力作用，静止的物体始终静止，运动的物体一直作匀速直线运动。
The tendency of a body to resist acceleration; the tendency of a body at rest to remain at rest or of a body in motion to stay in motion in a straight line unless acted on by an outside force. 惯性物体抗拒加速的倾向；在没有外力作用的情况下，静止的物体保持静止状态的倾向，或运动着的物体保持匀速直线运动的倾向
A ghost?A body in search of a soul? 一个幽灵?还是寻找灵魂的行尸走肉?
We see bodies in motion here and there. 我们到处都可以看见物体在运动。