could shorten
Regular verb: shorten - shortened- shortened

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could shorten
you could shorten
she could shorten
we could shorten
you could shorten
they could shorten 	I could be shortening
you could be shortening
she could be shortening
we could be shortening
you could be shortening
they could be shortening	I could have shortened
you could have shortened
she could have shortened
we could have shortened
you could have shortened
they could have shortened	I could have been shortening
you could have been shortening
she could have been shortening
we could have been shortening
you could have been shortening
they could have been shortening	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could not shorten
you could not shorten
she could not shorten
we could not shorten
you could not shorten
they could not shorten 	I could not be shortening
you could not be shortening
she could not be shortening
we could not be shortening
you could not be shortening
they could not be shortening	I could not have shortened
you could not have shortened
she could not have shortened
we could not have shortened
you could not have shortened
they could not have shortened	I could not have been shortening
you could not have been shortening
she could not have been shortening
we could not have been shortening
you could not have been shortening
they could not have been shortening	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I shorten?
could you shorten?
could she shorten?
could we shorten?
could you shorten?
could they shorten? 	could I be shortening?
could you be shortening?
could she be shortening?
could we be shortening?
could you be shortening?
could they be shortening? 	could I have shortened?
could you have shortened?
could she have shortened?
could we have shortened?
could you have shortened?
could they have shortened? 	could I have been shortening?
could you have been shortening?
could she have been shortening?
could we have been shortening?
could you have been shortening?
could they have been shortening? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I not shorten?
could you not shorten?
could she not shorten?
could we not shorten?
could you not shorten?
could they not shorten? 	could I not be shortening?
could you not be shortening?
could she not be shortening?
could we not be shortening?
could you not be shortening?
could they not be shortening? 	could I not have shortened?
could you not have shortened?
could she not have shortened?
could we not have shortened?
could you not have shortened?
could they not have shortened? 	could I not have been shortening?
could you not have been shortening?
could she not have been shortening?
could we not have been shortening?
could you not have been shortening?
could they not have been shortening?