I have no doors but I have keys, I have no rooms but I have space, you can enter but you can’t leave! What am I?

Decode this picture on T-Shirt and tell what it says ?

A B C D E F G H

These are the letters given to you. Now you have to find out the letter that comes two to the right of the letter which is immediately to the left of the letter that comes three to the right of the letter that comes midway between the letter two to the left of the letter C and the letter immediately to the right of the letter F.

In 1990, a person is 15 years old. In 1995, that same person is 10 years old. How can this be?

You are given a cube that is made with the help of 10x10x10 smaller cubes summing up to a total of 1000 smaller cubes. You are asked to take off one layer of the cubes.
How many remain now?

It is always ahead of me yet I can never see it. What is it?

You see a boat filled with people, yet there isn’t a single person on board. How is that possible?

I am a type of word that is spelt incorrectly or used differently, on purpose for humour. What am I?
Hint 1: You can find me in a joke.
Hint 2: I am a play on words.

Look at this sequence from top to bottom. What is the next number in the sequence?
1
11
21
1211
111221
312211

Which English verb becomes past tense just by rearranging the letters?