I could restraighten you could restraighten he could restraighten we could restraighten you could restraighten they could restraighten
V-ing form
I could be restraightening you could be restraightening he could be restraightening we could be restraightening you could be restraightening they could be restraightening
Perfect
I could have restraightened you could have restraightened he could have restraightened we could have restraightened you could have restraightened they could have restraightened
V-ing perfect
I could have been restraightening you could have been restraightening he could have been restraightening we could have been restraightening you could have been restraightening they could have been restraightening
Negation
Simple form
I couldn't restraighten you couldn't restraighten he couldn't restraighten we couldn't restraighten you couldn't restraighten they couldn't restraighten
V-ing form
I couldn't be restraightening you couldn't be restraightening he couldn't be restraightening we couldn't be restraightening you couldn't be restraightening they couldn't be restraightening
Perfect
I couldn't have restraightened you couldn't have restraightened he couldn't have restraightened we couldn't have restraightened you couldn't have restraightened they couldn't have restraightened
V-ing perfect
I couldn't have been restraightening you couldn't have been restraightening he couldn't have been restraightening we couldn't have been restraightening you couldn't have been restraightening they couldn't have been restraightening
Interrogative form
Simple form
could I restraighten? could you restraighten? could he restraighten? could we restraighten? could you restraighten? could they restraighten?
V-ing form
could I be restraightening? could you be restraightening? could he be restraightening? could we be restraightening? could you be restraightening? could they be restraightening?
Perfect
could I have restraightened? could you have restraightened? could he have restraightened? could we have restraightened? could you have restraightened? could they have restraightened?
V-ing perfect
could I have been restraightening? could you have been restraightening? could he have been restraightening? could we have been restraightening? could you have been restraightening? could they have been restraightening?
Interro-negative form
Simple form
couldn't I restraighten? couldn't you restraighten? couldn't he restraighten? couldn't we restraighten? couldn't you restraighten? couldn't they restraighten?
V-ing form
couldn't I be restraightening? couldn't you be restraightening? couldn't he be restraightening? couldn't we be restraightening? couldn't you be restraightening? couldn't they be restraightening?
Perfect
couldn't I have restraightened? couldn't you have restraightened? couldn't he have restraightened? couldn't we have restraightened? couldn't you have restraightened? couldn't they have restraightened?
V-ing perfect
couldn't I have been restraightening? couldn't you have been restraightening? couldn't he have been restraightening? couldn't we have been restraightening? couldn't you have been restraightening? couldn't they have been restraightening?