呵呵，在中国上课迟到了都打“报告！”。。。

在汉语的句子中，说话人经常会省略掉主语，人们会根据语境推测出说话人的意思。“可以进来吗？”从严格的意义上说是一个缺少主语的病句，但是符合中国人日常用语习惯。不过，出于礼貌，您应该在说话时添上主语，“我能进来吗”。In Chinese, the subject of a sentence is often left, but people can still understand it according to the situation. "可以进来吗？" is a wrong sentence with no subject, considering standered grammer. however, it"s just what Chinese people may say in their daily life. But in order to show you are polite, you'd better add a subject and say"我能进来吗？"

不用问直接进就行了。哈哈。

In English, 疑问句是将动词放到句首，而In Chinese,疑问句是在正常语句的句末加语气助词“么”或者“呢”或者“吗”等。所以may(可以) I(我) come in(进来)应该翻译成 我可以进来么？

thats right!but maybe 请问？我能进来吗？is better