I travel all around the world but always stay in the corner. What am I?

Can you tell a 3D object that has just two surfaces?

They came out at night, without being called.
They lost at day, without being stolen.
Who are they?

A man is approaching a broad and barren land. He has a package with him. If somehow, he is unable to open the package before reaching the land, he will die.

Can you guess what is present in the package?

I have one of the three numbers: 1, 2, or 3 in my mind. I speak only truth. You can ask me just one question for which I will only reply in yes or no or don't know. What question will you ask from me so that you are able to know the number?

In particular commonwealth games, a female participant won silver and gold medals for a single event.

How can this be possible?

Can you name some countries which do not have the alphabet 'A' in them?

I have an eye but still cannot see.

Who am I?

Christina has four daughters, and each of her daughters has a brother. How many children does Christina have?

Can you think of any three-dimensional shape that comprises of exactly two surfaces?