我将放弃学中文；我把车停了；别再那样做了。

It sounds to me you are still trying to translate word for word. That doesn't really work. You need to translate for the situation, context and feeling. For example: I will stop learning Chinese. I could say 我会放弃学习中文 （Literally， I will give up studying Chinese ）or I could say 我再也不会学中文了- I will never study Chinese again. There are others I might use too. I stopped the car. 我停下车, or something similar along these lines Stop doing that: Again there are so many ways to translate this depending on what the person is doing. For example I might say 别动 if I want someone to stop moving, or even if I caught my kids doing something naughty, or I might say 别说了 if I want someone to stop talking. I might also say 不要 （不要再）then add what ever the person is doing.

I will stop learning Chinese. 我停止学习中文 I stopped the car. 我停车 Stop doing that. 住手

I will stop learning Chinese. 我不再學中文了 I stopped the car. 我停下車 Stop doing that. 別再這樣了 Stop talking. 住口，別再說了 Stop hitting me. 住手，別再打我了 Stop walking. 站住，別動

stop –停止，阻止，停下 The car stopped。车停下来了。 The rain stopped.雨停了。 Do not stop me.别阻止我 Please dont stop the music 别停下音乐 Stop ! 停! Stop it! 够了! Hope this answer is clear to understand!