could lower
Regular verb: lower - lowered- lowered

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could lower
you could lower
she could lower
we could lower
you could lower
they could lower 	I could be lowering
you could be lowering
she could be lowering
we could be lowering
you could be lowering
they could be lowering	I could have lowered
you could have lowered
she 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
she 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 couldn't lower
you couldn't lower
she couldn't lower
we couldn't lower
you couldn't lower
they couldn't lower 	I couldn't be lowering
you couldn't be lowering
she couldn't be lowering
we couldn't be lowering
you couldn't be lowering
they couldn't be lowering	I couldn't have lowered
you couldn't have lowered
she couldn't have lowered
we couldn't have lowered
you couldn't have lowered
they couldn't have lowered	I couldn't have been lowering
you couldn't have been lowering
she couldn't have been lowering
we couldn't have been lowering
you couldn't have been lowering
they couldn't have been lowering	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I lower?
could you lower?
could she lower?
could we lower?
could you lower?
could they lower? 	could I be lowering?
could you be lowering?
could she be lowering?
could we be lowering?
could you be lowering?
could they be lowering? 	could I have lowered?
could you have lowered?
could she 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 she 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 	
couldn't I lower?
couldn't you lower?
couldn't she lower?
couldn't we lower?
couldn't you lower?
couldn't they lower? 	couldn't I be lowering?
couldn't you be lowering?
couldn't she be lowering?
couldn't we be lowering?
couldn't you be lowering?
couldn't they be lowering? 	couldn't I have lowered?
couldn't you have lowered?
couldn't she have lowered?
couldn't we have lowered?
couldn't you have lowered?
couldn't they have lowered? 	couldn't I have been lowering?
couldn't you have been lowering?
couldn't she have been lowering?
couldn't we have been lowering?
couldn't you have been lowering?
couldn't they have been lowering?