could mature
Regular verb: mature - matured- matured

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could mature
you could mature
he could mature
we could mature
you could mature
they could mature 	I could be maturing
you could be maturing
he could be maturing
we could be maturing
you could be maturing
they could be maturing	I could have matured
you could have matured
he could have matured
we could have matured
you could have matured
they could have matured	I could have been maturing
you could have been maturing
he could have been maturing
we could have been maturing
you could have been maturing
they could have been maturing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't mature
you couldn't mature
he couldn't mature
we couldn't mature
you couldn't mature
they couldn't mature 	I couldn't be maturing
you couldn't be maturing
he couldn't be maturing
we couldn't be maturing
you couldn't be maturing
they couldn't be maturing	I couldn't have matured
you couldn't have matured
he couldn't have matured
we couldn't have matured
you couldn't have matured
they couldn't have matured	I couldn't have been maturing
you couldn't have been maturing
he couldn't have been maturing
we couldn't have been maturing
you couldn't have been maturing
they couldn't have been maturing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I mature?
could you mature?
could he mature?
could we mature?
could you mature?
could they mature? 	could I be maturing?
could you be maturing?
could he be maturing?
could we be maturing?
could you be maturing?
could they be maturing? 	could I have matured?
could you have matured?
could he have matured?
could we have matured?
could you have matured?
could they have matured? 	could I have been maturing?
could you have been maturing?
could he have been maturing?
could we have been maturing?
could you have been maturing?
could they have been maturing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I mature?
couldn't you mature?
couldn't he mature?
couldn't we mature?
couldn't you mature?
couldn't they mature? 	couldn't I be maturing?
couldn't you be maturing?
couldn't he be maturing?
couldn't we be maturing?
couldn't you be maturing?
couldn't they be maturing? 	couldn't I have matured?
couldn't you have matured?
couldn't he have matured?
couldn't we have matured?
couldn't you have matured?
couldn't they have matured? 	couldn't I have been maturing?
couldn't you have been maturing?
couldn't he have been maturing?
couldn't we have been maturing?
couldn't you have been maturing?
couldn't they have been maturing?