can blacken
Regular verb: blacken - blackened- blackened

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I can blacken
you can blacken
she can blacken
we can blacken
you can blacken
they can blacken 	I can be blackening
you can be blackening
she can be blackening
we can be blackening
you can be blackening
they can be blackening	I can have blackened
you can have blackened
she can have blackened
we can have blackened
you can have blackened
they can have blackened	I can have been blackening
you can have been blackening
she can have been blackening
we can have been blackening
you can have been blackening
they can have been blackening	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I can't blacken
you can't blacken
she can't blacken
we can't blacken
you can't blacken
they can't blacken 	I can't be blackening
you can't be blackening
she can't be blackening
we can't be blackening
you can't be blackening
they can't be blackening	I can't have blackened
you can't have blackened
she can't have blackened
we can't have blackened
you can't have blackened
they can't have blackened	I can't have been blackening
you can't have been blackening
she can't have been blackening
we can't have been blackening
you can't have been blackening
they can't have been blackening	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
can I blacken?
can you blacken?
can she blacken?
can we blacken?
can you blacken?
can they blacken? 	can I be blackening?
can you be blackening?
can she be blackening?
can we be blackening?
can you be blackening?
can they be blackening? 	can I have blackened?
can you have blackened?
can she have blackened?
can we have blackened?
can you have blackened?
can they have blackened? 	can I have been blackening?
can you have been blackening?
can she have been blackening?
can we have been blackening?
can you have been blackening?
can they have been blackening? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
can't I blacken?
can't you blacken?
can't she blacken?
can't we blacken?
can't you blacken?
can't they blacken? 	can't I be blackening?
can't you be blackening?
can't she be blackening?
can't we be blackening?
can't you be blackening?
can't they be blackening? 	can't I have blackened?
can't you have blackened?
can't she have blackened?
can't we have blackened?
can't you have blackened?
can't they have blackened? 	can't I have been blackening?
can't you have been blackening?
can't she have been blackening?
can't we have been blackening?
can't you have been blackening?
can't they have been blackening?