Good Riddles

Question: Which is correct, 9 and 5 is 13 or 9 plus 5 is 13?

Question: Half of those who read this riddle, I am your best friend.
I depend on you, but it's you I will defend.

What am I?

Question: Snow White had the dwarfs were having dinner. The dwarfs asked for more food so snow white got them more.

How many seconds did she take?

Question: I make up all literature, but I'm often sealed.

What am I?

Question: what are the next two letters in this sequence: A, E, F, H, I, K, L, M,