When you were talking to the policeman,I saw a teenager___

问题描述:

When you were talking to the policeman,I saw a teenager___
横线上为什么填get on your car,而不是getting on?
印象里see sb doing是看到某人正在做,see sb do是表经常看见的动作

在这个语境中是表示看到一个完整的事件,并不强调这个事件的过程.