Good Riddles

Question: Suppose you're on a game show, and you're given the choice of three doors: Behind one door is a sports car; behind all of the others is bicycles. You pick a door, say No. 1, and the host, who knows what's behind the doors, opens another door, say No. 2, revealing a bicycle. He then says to you, "Do you want to pick door No. 3?" Is it to your advantage to switch your choice?

Question: I dig out tiny caves, and store gold and silver in them. I also build bridges of silver and make crowns of gold. They are the smallest you could imagine. Sooner or later everybody needs my help, yet many people are afraid to let me help them. Who am I?

Question: To get to the word SCARY to ALONE, changing only one letter at a time to make 8 different words including SCARY and ALONE.

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

What am I?

Question: Which eight-letter word still remains a word after removing each letter from it?