英语 短文改错 10处.. 不是很长的

I am a high school student. A few days before(改成ago）, one of my close friend（加s） told me that he was going to stop the（the去掉） school. He said that he wanted to start his own business. I tried my best to get him （加to）change his mind,but I failed. I know that（that改成it） is difficult for him to change his mind. He is not doing so good（改成well） at his studies, yet（改成but） I want to advise him to have a try.
Now there is（改成are） only 90 days left after（改成before） the final exam. I don't know what to do. Could you give me any（改成some） advice?

括号中是改过之处.

I am a high school student. A few days (ago), one of my close (friends) told me that he was going to stop (his study at) the school. He said that he wanted to start his own business. I tried my best to ( 去掉get him ) change his mind,but I failed, I know (it) is difficult for him to change his mind. He is not doing so (well) at his studies,yet I want to advise him to have a try.
Now there (are) only 90 days left (be