1. The moon is moving around the earth every 28 days OR
The moon moves around the Earth every 28 days
2. Mark´s wanting to go to laboratory OR
Mark wants to go to the laboratory
3. How many people have study right now? OR
How many people are studying right now?
4. I´m liking your haircut
This means, I'm just getting used to it, not quite sure, might be all right.
I think you mean to say
I like your haircut.
5. My girlfriend is loving aerobics
My girlfriend loves aerobics.
Student or Learner