English verb conjugation
COULD TAXI

Regular verb: taxi - taxied - taxied

Affirmation

Simple form	V-ing form
I could taxi you could taxi he could taxi we could taxi you could taxi they could taxi	I could be taxiing you could be taxiing he could be taxiing we could be taxiing you could be taxiing they could be taxiing
Perfect	V-ing perfect
I could have taxied you could have taxied he could have taxied we could have taxied you could have taxied they could have taxied	I could have been taxiing you could have been taxiing he could have been taxiing we could have been taxiing you could have been taxiing they could have been taxiing

Negation

Simple form	V-ing form
I couldn't taxi you couldn't taxi he couldn't taxi we couldn't taxi you couldn't taxi they couldn't taxi	I couldn't be taxiing you couldn't be taxiing he couldn't be taxiing we couldn't be taxiing you couldn't be taxiing they couldn't be taxiing
Perfect	V-ing perfect
I couldn't have taxied you couldn't have taxied he couldn't have taxied we couldn't have taxied you couldn't have taxied they couldn't have taxied	I couldn't have been taxiing you couldn't have been taxiing he couldn't have been taxiing we couldn't have been taxiing you couldn't have been taxiing they couldn't have been taxiing

Interrogative form

Simple form	V-ing form
could I taxi? could you taxi? could he taxi? could we taxi? could you taxi? could they taxi?	could I be taxiing? could you be taxiing? could he be taxiing? could we be taxiing? could you be taxiing? could they be taxiing?
Perfect	V-ing perfect
could I have taxied? could you have taxied? could he have taxied? could we have taxied? could you have taxied? could they have taxied?	could I have been taxiing? could you have been taxiing? could he have been taxiing? could we have been taxiing? could you have been taxiing? could they have been taxiing?

Interro-negative form

Simple form	V-ing form
couldn't I taxi? couldn't you taxi? couldn't he taxi? couldn't we taxi? couldn't you taxi? couldn't they taxi?	couldn't I be taxiing? couldn't you be taxiing? couldn't he be taxiing? couldn't we be taxiing? couldn't you be taxiing? couldn't they be taxiing?
Perfect	V-ing perfect
couldn't I have taxied? couldn't you have taxied? couldn't he have taxied? couldn't we have taxied? couldn't you have taxied? couldn't they have taxied?	couldn't I have been taxiing? couldn't you have been taxiing? couldn't he have been taxiing? couldn't we have been taxiing? couldn't you have been taxiing? couldn't they have been taxiing?