can slacken
Regular verb: slacken - slackened- slackened

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I can slacken
you can slacken
she can slacken
we can slacken
you can slacken
they can slacken 	I can be slackening
you can be slackening
she can be slackening
we can be slackening
you can be slackening
they can be slackening	I can have slackened
you can have slackened
she can have slackened
we can have slackened
you can have slackened
they can have slackened	I can have been slackening
you can have been slackening
she can have been slackening
we can have been slackening
you can have been slackening
they can have been slackening	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I cannot slacken
you cannot slacken
she cannot slacken
we cannot slacken
you cannot slacken
they cannot slacken 	I cannot be slackening
you cannot be slackening
she cannot be slackening
we cannot be slackening
you cannot be slackening
they cannot be slackening	I cannot have slackened
you cannot have slackened
she cannot have slackened
we cannot have slackened
you cannot have slackened
they cannot have slackened	I cannot have been slackening
you cannot have been slackening
she cannot have been slackening
we cannot have been slackening
you cannot have been slackening
they cannot have been slackening	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
can I slacken?
can you slacken?
can she slacken?
can we slacken?
can you slacken?
can they slacken? 	can I be slackening?
can you be slackening?
can she be slackening?
can we be slackening?
can you be slackening?
can they be slackening? 	can I have slackened?
can you have slackened?
can she have slackened?
can we have slackened?
can you have slackened?
can they have slackened? 	can I have been slackening?
can you have been slackening?
can she have been slackening?
can we have been slackening?
can you have been slackening?
can they have been slackening? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
can I not slacken?
can you not slacken?
can she not slacken?
can we not slacken?
can you not slacken?
can they not slacken? 	can I not be slackening?
can you not be slackening?
can she not be slackening?
can we not be slackening?
can you not be slackening?
can they not be slackening? 	can I not have slackened?
can you not have slackened?
can she not have slackened?
can we not have slackened?
can you not have slackened?
can they not have slackened? 	can I not have been slackening?
can you not have been slackening?
can she not have been slackening?
can we not have been slackening?
can you not have been slackening?
can they not have been slackening?