could overstrain
Regular verb: overstrain - overstrained- overstrained

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could overstrain
you could overstrain
he could overstrain
we could overstrain
you could overstrain
they could overstrain 	I could be overstraining
you could be overstraining
he could be overstraining
we could be overstraining
you could be overstraining
they could be overstraining	I could have overstrained
you could have overstrained
he could have overstrained
we could have overstrained
you could have overstrained
they could have overstrained	I could have been overstraining
you could have been overstraining
he could have been overstraining
we could have been overstraining
you could have been overstraining
they could have been overstraining	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't overstrain
you couldn't overstrain
he couldn't overstrain
we couldn't overstrain
you couldn't overstrain
they couldn't overstrain 	I couldn't be overstraining
you couldn't be overstraining
he couldn't be overstraining
we couldn't be overstraining
you couldn't be overstraining
they couldn't be overstraining	I couldn't have overstrained
you couldn't have overstrained
he couldn't have overstrained
we couldn't have overstrained
you couldn't have overstrained
they couldn't have overstrained	I couldn't have been overstraining
you couldn't have been overstraining
he couldn't have been overstraining
we couldn't have been overstraining
you couldn't have been overstraining
they couldn't have been overstraining	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I overstrain?
could you overstrain?
could he overstrain?
could we overstrain?
could you overstrain?
could they overstrain? 	could I be overstraining?
could you be overstraining?
could he be overstraining?
could we be overstraining?
could you be overstraining?
could they be overstraining? 	could I have overstrained?
could you have overstrained?
could he have overstrained?
could we have overstrained?
could you have overstrained?
could they have overstrained? 	could I have been overstraining?
could you have been overstraining?
could he have been overstraining?
could we have been overstraining?
could you have been overstraining?
could they have been overstraining? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I overstrain?
couldn't you overstrain?
couldn't he overstrain?
couldn't we overstrain?
couldn't you overstrain?
couldn't they overstrain? 	couldn't I be overstraining?
couldn't you be overstraining?
couldn't he be overstraining?
couldn't we be overstraining?
couldn't you be overstraining?
couldn't they be overstraining? 	couldn't I have overstrained?
couldn't you have overstrained?
couldn't he have overstrained?
couldn't we have overstrained?
couldn't you have overstrained?
couldn't they have overstrained? 	couldn't I have been overstraining?
couldn't you have been overstraining?
couldn't he have been overstraining?
couldn't we have been overstraining?
couldn't you have been overstraining?
couldn't they have been overstraining?