could mothball
Regular verb: mothball - mothballed- mothballed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could mothball
you could mothball
she could mothball
we could mothball
you could mothball
they could mothball 	I could be mothballing
you could be mothballing
she could be mothballing
we could be mothballing
you could be mothballing
they could be mothballing	I could have mothballed
you could have mothballed
she could have mothballed
we could have mothballed
you could have mothballed
they could have mothballed	I could have been mothballing
you could have been mothballing
she could have been mothballing
we could have been mothballing
you could have been mothballing
they could have been mothballing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't mothball
you couldn't mothball
she couldn't mothball
we couldn't mothball
you couldn't mothball
they couldn't mothball 	I couldn't be mothballing
you couldn't be mothballing
she couldn't be mothballing
we couldn't be mothballing
you couldn't be mothballing
they couldn't be mothballing	I couldn't have mothballed
you couldn't have mothballed
she couldn't have mothballed
we couldn't have mothballed
you couldn't have mothballed
they couldn't have mothballed	I couldn't have been mothballing
you couldn't have been mothballing
she couldn't have been mothballing
we couldn't have been mothballing
you couldn't have been mothballing
they couldn't have been mothballing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I mothball?
could you mothball?
could she mothball?
could we mothball?
could you mothball?
could they mothball? 	could I be mothballing?
could you be mothballing?
could she be mothballing?
could we be mothballing?
could you be mothballing?
could they be mothballing? 	could I have mothballed?
could you have mothballed?
could she have mothballed?
could we have mothballed?
could you have mothballed?
could they have mothballed? 	could I have been mothballing?
could you have been mothballing?
could she have been mothballing?
could we have been mothballing?
could you have been mothballing?
could they have been mothballing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I mothball?
couldn't you mothball?
couldn't she mothball?
couldn't we mothball?
couldn't you mothball?
couldn't they mothball? 	couldn't I be mothballing?
couldn't you be mothballing?
couldn't she be mothballing?
couldn't we be mothballing?
couldn't you be mothballing?
couldn't they be mothballing? 	couldn't I have mothballed?
couldn't you have mothballed?
couldn't she have mothballed?
couldn't we have mothballed?
couldn't you have mothballed?
couldn't they have mothballed? 	couldn't I have been mothballing?
couldn't you have been mothballing?
couldn't she have been mothballing?
couldn't we have been mothballing?
couldn't you have been mothballing?
couldn't they have been mothballing?