男女同桌之间常有一条“楚河汉界”，绝不能越雷池一步。因此，同桌往往形同陌路人。这种现象说明（）
①这样可以避免许多不必要的麻烦
②这是对男女同学交往的错误理解和做法
③这种做法只能使同学们对异性交往过于敏感、拘谨，产生心理障碍
④这种现象是正常的，它可以避免男女生之间的“早恋”发生 

阅读理解

    Good morning．Welcome to our school!

    My name is Hou Li，a history teacher.I'm your guide today．Look!Our big playground lies in the middle of the school．On the left of it are two black classroom buildings．There are thirty classrooms in each building．We use computers to help with teaching．It's quick and saves much time．We also put important information on the Internet．so our students can read it at home．Of course,they do their homework on the computers too，just like your students in America．We're going to join an IT lesson at nine o'clock there．

    On the right are three buildings：the office building,the dining hall and the library．The dining hall is orange．Six hundred students can eat in it at a time．Today we are going to have lunch there．The library is a popular place．There are many kinds of magazines and newspapers and hundreds of books for students and teachers．

    Let's have a rest near the office building and then go to the IT lesson．

根据材料内容选择最佳答案。