What Comes Once, Twice and Never

What five-letter word becomes shorter if you add two letters to it?

Can you name the four days of the week that begin with letter "T"

I am the nearest planet to the sun.

I am the smallest planet in the solar system.

Who am I?

I am a farm animal. I eat grass.

I am big and intelligent. I carry people and things.

I help with work. I run quickly.

What am I?

I am found in the freezer. I taste good on a sunny day.

I come in many different flavours. I am made of cream.

What am I?