What month of the year has 28 days?

Pronounced as one letter,
And written with three,
Two letters there are,
And two only in me.
I am double, I am single,
I am black blue and grey,
I am read from both ends,
And the same either way.

Count The number of F's in the paragraph below:

"FINISHED FILES ARE THE RESULT OF YEARS OF SCIENTIFIC STUDY COMBINED WITH THE EXPERIENCE OF YEARS"

He does not have any heart but still, He manages to live.
If you kill him, you will eventually die but yet you kill him.
He cannot run, who is He?

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?

What is more useful when it is broken?

When I get multiplied by any number, the sum of the figures in the product is always me. What am I?

I sleep during the day and fly at night, but I have no feathers to aid my flight. What am I?

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

What Word am I Looking For ?

There are five vowels (a, e, i, o, u) in the English language.
Can you tell us a word that contains all these vowels?