Can you make four (4) nines (9) equal 100?

I have a hole in my back and legs I lack.
I live where I can’t breathe and I eat without teeth.
What am I?

What will you call your mother's brother's brother-in-law?

A pack of cards has 40 cards. You are blindfolded. Out of 40, 25 cards are facing down while 15 are facing up. You have been asked to divide this pack of cards into two decks - so that each deck contains an equal number of face-up cards. Remember, you are blindfolded.

How will you do it?

Using the clues below, what four numbers am I thinking of?

The sum of all the numbers is 31.
One number is odd.
The highest number minus the lowest number is 7.
If you subtract the middle two numbers, it equals two.
There are no duplicate numbers.

Can you circle exactly four of these numbers such that the total is twelve?

1 6 1
6 1 6
1 6 1
6 1 6

What can you catch but never throw?

Why do we preferably have round manhole covers and not square ones?

Arrange the numbers 1, 2, 3, 4, 5, 6, 7, 8 and 9 above and below the division line in a manner that the thus formed fractions equal to 1/3.

(You can use one number only once)

It's a protector.
It sits on a bridge.
One individual can see directly through it, while others wonder what it hides.

What is it?