Good Riddles

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

What am I?

Question: I am a digit, but two of the ten.
Two of me make a promise.

What am I?

Question: I'm the part of a bird that's not in the sky,
I can swim in the ocean and remain dry?

What am I?

Question: You have a flashlight that takes 2 working batteries. You have 8 batteries but only 4 of them work.

What is the fewest number of pairs you need to test to guarantee you can get the flashlight on?