Tìm lỗi sai trong đoạn văn sau:

Tìm lỗi sai trong đoạn văn sau:\
Dear dad,

Thank you for your email. I have been busy with school lately, we are about to have our end 25.  semester exams. Last week I tried to call you, but I couldn’t get 26. . I just wanted to tell you that a few weeks ago, my teacher told me that I have been doing very well at school, but 27.  need to focus more on Mathematics. My scores in the last math’s exam were below average. I am not sure 28.   can improve these scores because I have so many subjects to focus on at the moment. Do you have any ideas? My grades for all my other subjects have been fantastic, but 29.  you know, my math’s scores must be above average, otherwise, I might not 30.  into medical school.
Please help!!!
Susie.