1)  You can use a computer, if you have a job.

2)  You can't watch TV. You haven't done your hpmework yet.

3)  Students can't use calculators in math classes.

4)  Can I take your suitcase?

5)  Can I borrow your car, please?

6)  He can't stay with us.

7)  You can't leave your car here.

8) He can join us, if he wants.

9)  Can I see your calculations, please?

10) Can i have an apple? - First, you should wash your hands and then you can take an apple.