could straighten
Regular verb: straighten - straightened- straightened

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could straighten
you could straighten
he could straighten
we could straighten
you could straighten
they could straighten 	I could be straightening
you could be straightening
he could be straightening
we could be straightening
you could be straightening
they could be straightening	I could have straightened
you could have straightened
he could have straightened
we could have straightened
you could have straightened
they could have straightened	I could have been straightening
you could have been straightening
he could have been straightening
we could have been straightening
you could have been straightening
they could have been straightening	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could not straighten
you could not straighten
he could not straighten
we could not straighten
you could not straighten
they could not straighten 	I could not be straightening
you could not be straightening
he could not be straightening
we could not be straightening
you could not be straightening
they could not be straightening	I could not have straightened
you could not have straightened
he could not have straightened
we could not have straightened
you could not have straightened
they could not have straightened	I could not have been straightening
you could not have been straightening
he could not have been straightening
we could not have been straightening
you could not have been straightening
they could not have been straightening	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I straighten?
could you straighten?
could he straighten?
could we straighten?
could you straighten?
could they straighten? 	could I be straightening?
could you be straightening?
could he be straightening?
could we be straightening?
could you be straightening?
could they be straightening? 	could I have straightened?
could you have straightened?
could he have straightened?
could we have straightened?
could you have straightened?
could they have straightened? 	could I have been straightening?
could you have been straightening?
could he have been straightening?
could we have been straightening?
could you have been straightening?
could they have been straightening? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I not straighten?
could you not straighten?
could he not straighten?
could we not straighten?
could you not straighten?
could they not straighten? 	could I not be straightening?
could you not be straightening?
could he not be straightening?
could we not be straightening?
could you not be straightening?
could they not be straightening? 	could I not have straightened?
could you not have straightened?
could he not have straightened?
could we not have straightened?
could you not have straightened?
could they not have straightened? 	could I not have been straightening?
could you not have been straightening?
could he not have been straightening?
could we not have been straightening?
could you not have been straightening?
could they not have been straightening?