Answer:
I help you carry your books.
I can be swallowed, but I can also swallow you. What am I?
I am a ship that can be made to ride the greatest waves. I am not built by objects, but built by minds. What am I?
A dragons tooth in a mortals hand I kill I maim I divide the land.
I hold two people together but touch only one. What am I?
I tell people to be careful when handling boxes.