What has one letter and starts with an E?

What word begins and ends with an E, but has only one letter?

In a mathematical quiz, you are asked the following question:

Use three 9s in a mathematical expression without dividing or multiplying to form the number one.

Can you answer the question?

A new clothing store has a unique method of pricing items. A vest costs $20, a tie costs $15, a blouse costs $30, and underwear costs $45. How much would pants cost?

The more it dries, the wetter it becomes. Can you tell what it is?

A girl says this to her best friend: “I was born in 1955, and I celebrated my 17th birthday last weekend.” Her best friend thinks she’s lying, but she’s actually correct. How is that possible?

I welcome the day with a show of light, I stealthily came here in the night. I bathe the earthy stuff at dawn, But by noon, alas! I'm gone.

Your mother’s brother’s only brother-in-law is asleep on your couch. Who is asleep on your couch?

By adding four matchsticks, can you divide the square shown in the picture into two equal parts?

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

What Word am I Looking For ?