I could lift you could lift he could lift we could lift you could lift they could lift
V-ing form
I could be lifting you could be lifting he could be lifting we could be lifting you could be lifting they could be lifting
Perfect
I could have lifted you could have lifted he could have lifted we could have lifted you could have lifted they could have lifted
V-ing perfect
I could have been lifting you could have been lifting he could have been lifting we could have been lifting you could have been lifting they could have been lifting
Negation
Simple form
I could not lift you could not lift he could not lift we could not lift you could not lift they could not lift
V-ing form
I could not be lifting you could not be lifting he could not be lifting we could not be lifting you could not be lifting they could not be lifting
Perfect
I could not have lifted you could not have lifted he could not have lifted we could not have lifted you could not have lifted they could not have lifted
V-ing perfect
I could not have been lifting you could not have been lifting he could not have been lifting we could not have been lifting you could not have been lifting they could not have been lifting
Interrogative form
Simple form
could I lift? could you lift? could he lift? could we lift? could you lift? could they lift?
V-ing form
could I be lifting? could you be lifting? could he be lifting? could we be lifting? could you be lifting? could they be lifting?
Perfect
could I have lifted? could you have lifted? could he have lifted? could we have lifted? could you have lifted? could they have lifted?
V-ing perfect
could I have been lifting? could you have been lifting? could he have been lifting? could we have been lifting? could you have been lifting? could they have been lifting?
Interro-negative form
Simple form
could I not lift? could you not lift? could he not lift? could we not lift? could you not lift? could they not lift?
V-ing form
could I not be lifting? could you not be lifting? could he not be lifting? could we not be lifting? could you not be lifting? could they not be lifting?
Perfect
could I not have lifted? could you not have lifted? could he not have lifted? could we not have lifted? could you not have lifted? could they not have lifted?
V-ing perfect
could I not have been lifting? could you not have been lifting? could he not have been lifting? could we not have been lifting? could you not have been lifting? could they not have been lifting?