Good Riddles

Question: An electric train is traveling south. Which way does the smoke go?

Question: Had by few but treasured by all,
I'm on the inside and outside and I make men fall.

What am I?

Question: A pet shop owner had a parrot with a sign on its cage that said "Parrot repeats everything it hears." A young man bought the parrot and for two weeks he spoke to it but it didn't say a word. He tried to return the parrot but the shopkeeper said he never lied.

How can this be?

Question: A man drops an egg onto the cement. The egg doesn't break after falling 3 feet.

How could this be?

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

What am I?