Always in you, Sometimes on you;

If I surround you, I can kill you.

What am I?

John enters a small room. The Door Closes.
When the door opens, John is in a larger room.

Explain?

What has many keys but can’t open a single lock?

I am a normal creature, but I have five hands. I can even have more but even then I will be considered normal.

Who am I?

Begin with a word, five letters to my name,
Remove the first and last but I am the same
Take out my middle and still, I remain.
What word am I?

A man calls his dog from the opposite side of a river. The dog crosses the river without a bridge or a boat and manages to not get wet. How is this possible?

How many letters are in the alphabet?

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?

Can you name any English verb that becomes its past tense by simply rearranging the alphabets ?

The more you take me, the more you leave me behind.
Who Am I?