13.  How are subways and buses different?

Subways and buses are different because subways go underground and buses are above ground.

14.  Would you choose a bus or a subway to see the sights in a city?

I would choose a bus because a bus shows you more.  In a subway you can't really see anything because it's underground.

15.  What must you do before getting on an airplane?

Before getting on an airplane you show your ticket, go through security, and put your bag into storage.