Hello, Wangli! I am sorry to hear that you are much pressed now and often make mistakes in the exams. I think you should take some effective measures to deal with it .First I think you should be relaxed , keeping a good state of mind and having a positive attitude to the exams. In order to do that you should take more exercise and form a good habit of study and life. Besides you can listen to music to relax yourself. Finally you should turn to your teachers for help when you have problems.And you should set aside a few minutes to look through your test paper.Only in that way can you make fewer mistakes in exams.
Yours.
Lihua