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 couldn't lift you couldn't lift he couldn't lift we couldn't lift you couldn't lift they couldn't lift
V-ing form
I couldn't be lifting you couldn't be lifting he couldn't be lifting we couldn't be lifting you couldn't be lifting they couldn't be lifting
Perfect
I couldn't have lifted you couldn't have lifted he couldn't have lifted we couldn't have lifted you couldn't have lifted they couldn't have lifted
V-ing perfect
I couldn't have been lifting you couldn't have been lifting he couldn't have been lifting we couldn't have been lifting you couldn't have been lifting they couldn't 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
couldn't I lift? couldn't you lift? couldn't he lift? couldn't we lift? couldn't you lift? couldn't they lift?
V-ing form
couldn't I be lifting? couldn't you be lifting? couldn't he be lifting? couldn't we be lifting? couldn't you be lifting? couldn't they be lifting?
Perfect
couldn't I have lifted? couldn't you have lifted? couldn't he have lifted? couldn't we have lifted? couldn't you have lifted? couldn't they have lifted?
V-ing perfect
couldn't I have been lifting? couldn't you have been lifting? couldn't he have been lifting? couldn't we have been lifting? couldn't you have been lifting? couldn't they have been lifting?