English verb conjugation
COULD MATURE

Regular verb: mature - matured - matured

Affirmation

Simple form	V-ing form
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
Perfect	V-ing perfect
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
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
Perfect	V-ing perfect
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
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?
Perfect	V-ing perfect
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
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?
Perfect	V-ing perfect
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?