题目内容：

英语句子的表达是否正确,哪句错了,该怎么表达
1.)he is a doctor ,but he doesn't like it,because he thinks it's a busy and tired job.
2)he is a doctor ,but he doesn't like his job
3)I think study is very interesting
4)I think student is very interesting
5)I think doctor is boring
6)I think doctor is a boring job
7)he thinks his job is boring