English verb conjugation
CAN JACKKNIFE

Regular verb: jackknife - jackknifed - jackknifed

Affirmation

Simple form	V-ing form
I can jackknife you can jackknife he can jackknife we can jackknife you can jackknife they can jackknife	I can be jackknifing you can be jackknifing he can be jackknifing we can be jackknifing you can be jackknifing they can be jackknifing
Perfect	V-ing perfect
I can have jackknifed you can have jackknifed he can have jackknifed we can have jackknifed you can have jackknifed they can have jackknifed	I can have been jackknifing you can have been jackknifing he can have been jackknifing we can have been jackknifing you can have been jackknifing they can have been jackknifing

Negation

Simple form	V-ing form
I cannot jackknife you cannot jackknife he cannot jackknife we cannot jackknife you cannot jackknife they cannot jackknife	I cannot be jackknifing you cannot be jackknifing he cannot be jackknifing we cannot be jackknifing you cannot be jackknifing they cannot be jackknifing
Perfect	V-ing perfect
I cannot have jackknifed you cannot have jackknifed he cannot have jackknifed we cannot have jackknifed you cannot have jackknifed they cannot have jackknifed	I cannot have been jackknifing you cannot have been jackknifing he cannot have been jackknifing we cannot have been jackknifing you cannot have been jackknifing they cannot have been jackknifing

Interrogative form

Simple form	V-ing form
can I jackknife? can you jackknife? can he jackknife? can we jackknife? can you jackknife? can they jackknife?	can I be jackknifing? can you be jackknifing? can he be jackknifing? can we be jackknifing? can you be jackknifing? can they be jackknifing?
Perfect	V-ing perfect
can I have jackknifed? can you have jackknifed? can he have jackknifed? can we have jackknifed? can you have jackknifed? can they have jackknifed?	can I have been jackknifing? can you have been jackknifing? can he have been jackknifing? can we have been jackknifing? can you have been jackknifing? can they have been jackknifing?

Interro-negative form

Simple form	V-ing form
can I not jackknife? can you not jackknife? can he not jackknife? can we not jackknife? can you not jackknife? can they not jackknife?	can I not be jackknifing? can you not be jackknifing? can he not be jackknifing? can we not be jackknifing? can you not be jackknifing? can they not be jackknifing?
Perfect	V-ing perfect
can I not have jackknifed? can you not have jackknifed? can he not have jackknifed? can we not have jackknifed? can you not have jackknifed? can they not have jackknifed?	can I not have been jackknifing? can you not have been jackknifing? can he not have been jackknifing? can we not have been jackknifing? can you not have been jackknifing? can they not have been jackknifing?