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Today is Monday and it is the worst day of the week. Today the class had a standardized English and Mathematics test. Most of the students did not study because they played too much on Sunday.
In the class there are two naughty boys that never study for their tests. And this time they had too. same as before they did not study for their tests. They have an idea to solve the problem. They have a friend called Derek. He studies for every test and he gets good grades for every time.

Today was Monday and it was the worst day in the week. Today, there were an English and a Mathematics standardized test. Most of the students did not prepare for them because they played too much on Sunday.
In the class, there are two naughty boys who never study for their tests. ( What do you mean? They did revise for the tests this time or not?) They had an idea to solve the problem. They have a friend called Derek. He studies hard for every test and scores good grade every time.

It was Monday today and the worst day in the week. There were a standardized test of English and Mathematics. Most of the students haven't studied since they played too much on Sunday.
There were two naughty boys in the class that never studied for their test, but this time they haven't studied too. As they haven't studied, so they had an idea to solve the problem. They had a friend called Derek, Derek studied in each time and got a good mark everytime...

1.(Line 1) the worse day --> the worst day
2.(Line 2) did not study --> have not studied
3. (Line 4) that never study for their test
--> that have never studied for their tests
4. (Line 4) but this time they had too
--> and this time they had not too
5. (Line 5) study for their test --> study for their tests
6. (Line 5) They have an idea --> They had an idea
7. (Line 6) he got good marks for every time. .
--> he gets good marks every time ..