幫我作一個英文 Riddle (10) THX~

Riddle:
before you use it, it is black.
after you use it , it is white.
if it touches water, you can not use.
what is it?


IT IS COAL! (the thing used in bbq)

Joke:
What is ghosts favourite fruit?
BOOberry! (blueberry)

It is a square and big
Everybody can do it
It is fun, romantic and exciting,
What is It?

IS A TV
☆Hope Ican help You☆