What is always in front of you but can’t be seen?

What do you call a fish without an eye?

In this image, you can see three almost identical Doraemon images. Can you spot the odd one out from them?

A mile-long train is moving at sixty miles an hour when it reaches a mile-long tunnel. How long does it take the entire train to pass through the tunnel?

Two girls were born to the same mother, on the same day, at the same time, in the same month and year and yet they're not twins. How can this be ?

using four eights (8) and a one (1) and one mathematical symbol , create the number 100

What is the longest word in the dictionary?

In the Chess Board picture below white army is arranged. You need to add a black army on the board such that no piece is under any threat.
Note: Army comprised of 1 king, 1 queen, 2 rooks, 2 bishops, 2 knights, and 8 pawns.

Why do you find that most of the buildings are deprived of the 13th floor?

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?