1. Girls, today you will exercise/ will be exercising alternately.

It would be more natural to say "you will be taking turns exercising", but your example is grammatically correct.

First, Mary does/ will do /is doing her handstand, and Sophie makes/ will make/ is making sure Marie is keeping her body in a vertical line.

Your alternatives aren't grammatically incorrect, but in a situation where someone is explaining who will be doing what in a certain situation, the one that I left is the best choice. Your other two sound like describing what someone is doing from an outside perspective, perhaps at a later time.

No body-bending.

Then change (of switch (roles)/ then you changeswitch.

Sophie takes / will take/ is taking her turn to perform her handstand, and Mary corrects/ will correct/ is correcting her body position.

2. Can we leave the training 5 minutes earlier/ early today?

Yes, in exchange ofor good, hard work.

It would/ will be an exception this time.

3. He scored 35 % in/% on the test/ exam.

4. The mark was entered in the grade book under the rubric ofas a participation grade.

5. TakAssuming she'd like to get a final C or B in this subject, ther low score on the test from the first term should not affect her end of year GPA mark provided that she will intensifyincreases her participation in lessons, . Also, she must never get a failing mark for homework, report being unprepared for the lesson twice this term at the minimum and upgrad and increase all her E marks to C and B marks theat least.

I removed the part about reporting being unprepared because I have no idea what that means.

6.What sentence might be similar in meaning to JOHN HAS AN APPOINTMENT WITH THE DOCTOR ON MONDAY apart from"John has an appointment with the doctor on Monday" apart from "John is seeing the doctor on Monday"?

'John is seeing the doctor on Monday'?

Could it be: , "John is having an arranged meeting with the doctor on Monday"?

oOr maybe, "John is visiting a doctor on Monday", or '.......'"John is having a doctor's visit on Monday"?

I would just say "John has a doctor's appointment on Monday".

7. Is GEORGE IS THINKING OF STUDYING MEDICINE the same in meaning as GEORGE IS THINKING ABOUT STUDYING MEDICINE"George is thinking of studying medicine" the same in meaning as "George is thinking about studying medicine"?

Using all capitals is not a correct way to give an example. Also, those two are more or less the same, though there are slight differences depending on context. I would say the first sounds more like he's thinking about the actual process of studying medicine while the second sounds more like he is considering going into medical study.

Which of B's two answers is better?It depends on context.