Good Riddles

Question: Scientists are trying to figure out what is between Heaven and Earth.What is it?

Question: Sum Sam and Product Pete are in class when their teacher gives Sam the Sum of two numbers and Pete the product of the same two numbers (these numbers are greater than or equal to 2). They must figure out the two numbers.

Sam: I don't know what the numbers are Pete.
Pete: I knew you didn't know the numbers... But neither do I.
Sam: In that case, I do know the numbers.

What are the numbers?

Question: Why is a raven like a writing desk?

Question: Under pressure is the only way I work,
and by myself is the only way I'm hurt.

What am I?

Question: I take what you receive and surrender it all by waving my flag.What am I?