HOMEWORK CORRECTION: 

A.

I mostly walk 1.2km.  Lightly stretch before walking 

Better: I sometimes walk for 1.2km.​ I do lightly stretching before walking.

B.

I hope so.

By the way, why are you here?

=> Corrected: The sentences are corrected grammatically. 

I don't have any games on my new computer.

Better: There are no game programs in the new computer.