If I remove one from eleven it becomes Ten and if I remove one from nine also becomes Ten. How?

John was piloting a plane behind a car but was never able to overtake it. Why?

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

How many times can you subtract the number two from the number fifty?

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 times can you subtract the number 5 from 25?

Fate has decided that you will only be pleased to meet me when you need me

Maybe that is why, when I am working, I start working

However annoying I may be to the regulars, the little ones are always inspired

I will always be waiting if you try to reach me

How many of you can guess my name, let me see

I am looking for a word that change both gender and number when i add the letter 'S'.

What Word am I Looking For ?

I go up and I go down.
I go up towards the beautiful sky and down toward the green ground.
I am present tense.
I am past tense too
Children love me.

Who Am I?

When I go in I might cause pain. I cause you to spit and ask you not to swallow. I can fill your hole. What am I?