What is the riddle which can be asked all day with a different correct answer each time.

You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?

A Man gave one of his sons 10 cents and another son was given 15 cents. What time is it?
Hint: Figure out the relation between time and number, is not so easy..:)

The first person saw the bridge step on it and crossed,
the second person saw the bridge did not step on it but crossed,
the third person did not see the bridge did not step on it but crossed.
Who are these people?

Two in a corner, one in a room, zero in a house, but one in a shelter. What is it?

We have shown you a regular water barrel as below. Without using any measuring device can you check if the barrel is more than half-filled or less than half-filled?

You knock a Table over in the library, and suddenly 20 eyes are looking at you.

The centre of the third figure is empty. What digit should fit inside?

What is at the end of a rainbow?

A man lives on the fifteenth floor of an apartment building. Every morning he takes the elevator down to the lobby and leaves the building. In the evening, he gets into the elevator, and, if there is someone else in the elevator, or if it was raining that day, he goes back to his floor directly. Otherwise, he goes to the tenth floor and walks up five flights of stairs to his apartment. Can you explain why he does this?