Advantages:

we can use phone at the rest time.

-- We can use our phone during our break time.

We can call mom when some thing bad heppens.

-- We can call our moms if something bad happens.

Disadvantages:
other will play game at lessons.

-- Others will play games during class.

They will see pornography.
-- They might watch pornographic films or movies.

Not a warship out of a focus at the lessons.

-- They will be out of focus.

*Good job, Sky! Please take note of the corrections I made. You can use it for future studies. =)

-- Teacher Judy =)