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