The two old friends were ____ busy ____ with each other that they forgot the time.—Yes. They hadn’t met for over ten years, so they kept talking the whole night.

I will spend a whole evening _____ in your room waiting for the thief to arrive.

I can’t quite remember ________ you started playing golf.

up _______ youfell down, and I’m sure you’ll succeed in time

“It” is often used to a baby.