"I have not been to China." means 我没有去过中国。 “I need this. Please!” If you use this sentence when you are shopping, then that means 我要这个，谢谢。

• 我不去了中国。(I have not been to China) -- no, must be 我 没 去过 中国。 •我需要这.好吗! (I need this. Please!) -- no, must be "我 想 用 这 个 东西。请 给 我 吧!"