you don't stay out until late ,because you have a test tomorrow.不...答:通常情况下会说成:don't stay out until late ,because you have a test tomorrow,但是直接用don't打头,句子的语气会发生变化,变成了一个命令式的祈使句,而加上you,则能使语气较为委婉和温和,变成是建议式的一个句子,就是说“你还是不要再外面待得太晚了,你明天还有考试呢。”至于you要不要听这个建议,说...