This last year of highschool is draining my time and strength

This last year of highschool is draining my time and strength

Today I'm really tired! '¬¬

The last year of high school is very important for every brazilian student who wants to get into a University.  At the end of the year, we have to do the most important exam, the ENEM.  It's a national exam that opens the doors to Universities.  ENEM has 180 questions plus an essay.  We have two days to complete it, four and a half hours on the first day, plus one hour on the second day (when the essay is due). Courses in Engineering, Medicine and Law are the most (concurred??) common. I hope to be approved in Computer Science.

So, why am I tired?

Due to ENEM, private schools are tough in our last year.  After all, they want good results to attract more students.  I have, in addition to regular morning classes (7am to 12.50pm), afternoon classes on Mondays and Wednesdays and morning classes on Saturdays.  Tests are made on Tuesdays.  Today, I was at school from 7am to 12.50pm and from 3pm to 5.10pm.  This Saturday I have to do a big exam that simulates ENEM.  My school is part of an education network called COC, with about 450,000 students.  Recently, it was acquired by the British company PEARSON. better -> COC was recently acquired by PEARSON, a British company.

Your English is excellent, Douglas!  You are an amazing student.