Long Riddles and Answers

Question: It takes ten men ten hours to build a certain wall. How long does it take five men to build the same wall?

Question: How do you catch a giraffe? Giraffe bait. How do you catch a shark? Shark bait. How do you catch a master?

Question: A man looks out to a boat full of people But there's not a single person on board. How is this possible?

Question: When you need me, you throw me away. But when you're done with me, you bring me back.

What am I?

Question: I am shorter when I stand and taller when I sit.
Sometimes I'm even called a pit.

What am I?