There is no obligation for you to do it, if you don't want to.
You ________________, if you don't want to.

His car is so big you couldn't believe your eyes.
He has ___________ you couldn't believe your eyes.

I have never seen a man that tall.
It's ______________ a man that tall.

That girl is a friend of mine. His father owns El Corte Inglés.
That girl _____________ El Corte Inglés, is a friend of mine.

Tomorrow is Monday, but I would like it to be Sunday.
I ____________ Sunday.