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