What is the name given to a substance that increases the rate of a chemical reaction but is not itself consumed?

If Linh _______  (to ask) her teacher, he’d have answered her questions.

Huy _______ (try) to get a job for six months, but is still unemployed.

I _______________ spend too much money today. I’ve only got a little left.

He _______ (work) in a bank when he _______ (meet) his wife.

Dad _______ (to arrive) safe if he drove slowly.

We _______ (drive) to the movie theater, when we _______ (hit) a deer.

When I ________________________ (walk) into the room, everyone ________________________ (work).

You _______________ tidy up now. Your room’s a mess.

The door will unlock if you _______ (to press) the button.