Unit 17: AUXILIARY VERBS: "DO/ HAVE/ BE"
We can use do, have and be (Unit 3) as auxiliaries.
With do and have, we use only the base form, -s form or past form (not the -ing form or past participle -- Unit 14) this way.
This truck does not drive anymore.
Do you know why?
Did you drive it through the mud?
Use be + -ING FORM for continuous formations.
It is getting worse. (Present -- Unit 22)
Am I making sense? (Present -- Unit 22)
It was working last night. (Past -- Unit 23)
I must be working again soon. (with modals -- Unit 27)
We have been overworking it. (Perfect -- Unit 24)
Use be + PAST PARTICIPLE for passive formations.
Truck repairs are done in the city.
This truck will be driven there?
It is going to be fixed.
Use have + PAST PARTICIPLE for perfect formations.
Mud has become a big problem. (Present -- Unit 24)
Have you done your truck maintenance? (Present -- Unit 24)
I hadn't kept up with mine. (Past -- Unit 26)
I have been slacking. (Continuous -- Unit 24)
I must have lost it. (with modals -- Unit 27)
NOTICE: Do, have and be can also be lexical verbs (Unit 3):
Why did[auxiliary] you do[lexical] it?
I have[auxiliary] never been[lexical] there.
Has[auxiliary] he had[lexical] enough?
I am[lexical] tired.