forget + noun
I forgot the address.
forget + pronoun
Don’t forget him.
forget + about + noun
I almost forgot about the meeting.
forget + to + base form
Don’t forget to turn off the lights.
forget + clause
I forgot I had an appointment at 3 p.m.
forget + that + clause
I forgot that I had an appointment at 3 p.m.
forget + wh- clause
I forget how much I paid for that.