could lower
Regular verb: lower - lowered- lowered

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could lower
you could lower
he could lower
we could lower
you could lower
they could lower 	I could be lowering
you could be lowering
he could be lowering
we could be lowering
you could be lowering
they could be lowering	I could have lowered
you could have lowered
he could have lowered
we could have lowered
you could have lowered
they could have lowered	I could have been lowering
you could have been lowering
he could have been lowering
we could have been lowering
you could have been lowering
they could have been lowering	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could not lower
you could not lower
he could not lower
we could not lower
you could not lower
they could not lower 	I could not be lowering
you could not be lowering
he could not be lowering
we could not be lowering
you could not be lowering
they could not be lowering	I could not have lowered
you could not have lowered
he could not have lowered
we could not have lowered
you could not have lowered
they could not have lowered	I could not have been lowering
you could not have been lowering
he could not have been lowering
we could not have been lowering
you could not have been lowering
they could not have been lowering	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I lower?
could you lower?
could he lower?
could we lower?
could you lower?
could they lower? 	could I be lowering?
could you be lowering?
could he be lowering?
could we be lowering?
could you be lowering?
could they be lowering? 	could I have lowered?
could you have lowered?
could he have lowered?
could we have lowered?
could you have lowered?
could they have lowered? 	could I have been lowering?
could you have been lowering?
could he have been lowering?
could we have been lowering?
could you have been lowering?
could they have been lowering? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I not lower?
could you not lower?
could he not lower?
could we not lower?
could you not lower?
could they not lower? 	could I not be lowering?
could you not be lowering?
could he not be lowering?
could we not be lowering?
could you not be lowering?
could they not be lowering? 	could I not have lowered?
could you not have lowered?
could he not have lowered?
could we not have lowered?
could you not have lowered?
could they not have lowered? 	could I not have been lowering?
could you not have been lowering?
could he not have been lowering?
could we not have been lowering?
could you not have been lowering?
could they not have been lowering?