Indefinite pronouns (gap filling)

I am sure I put down my keys (a)  

Calm down. There is (a)   to worry about.

Let's sit down (a)   and talk.

I heard a knock at the door but there was (a)   there.

We didn't see (a)   :

The restaurant was really crowded. (a)   had a good time.

Be quiet! (a)   is coming!

I don't think (a)   knows the answer to that question.

She can't go (a)   without people recognizing her.

I've got (a)   to tell you.