can jackknife
Regular verb: jackknife - jackknifed- jackknifed

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