現在的中7學生發生什麼事

同佢同老豆老母講, 你個仔女無家教

I can feel your anger and discontentment. I agree with you that these S7 students are really arrogant and egotistic and they do suffer from megalomania.In fact, there are many grown-ups, not just the S7 students you mentioned, who are also conceited. Many people think highly of themselves and imagine themselves to be superior to others.Let's just ignore them and try our best to do our work. On the other hand, I have the least knowledge of your English standard.You said your English is just as good as those S7 students. I have a suggestion that you write your complaint in English, (the English version of this post) then post it in your blog or facebook and add your group members including those S7 students you mentioned to your blog/ facebook so that when they read your blog or facebook they can realize or assess your English standard.
Writing in English is a good way to practise and improve your English. You have just written a fairly long complaint about some people's English standard and that you are bewildered by this . Unfortunately it is written in Chinese I suggest that to further improve your English standard, from now on you should write more in English. Last but not least, having a degree majoring in English doesn't garantee the degree holder's English standard.