3:I helped John to learn Chinese every day,in return,he gave me a MP4 player last week.
4:After the earthquake,not any house nor any tree in the town stand still.
5:As parents,we should tell children that we trust them,which is good for them to develop a healthy personality.
楼上第五题不是定语从句啊,从句内有其指代的宾语怎么能算定语从句呢,另外两个完整句之间没有连接词是语法错误.第5题考察的是用which修饰一件事情,也就是非限定性定语从句.