I could frighten you could frighten she could frighten we could frighten you could frighten they could frighten
V-ing form
I could be frightening you could be frightening she could be frightening we could be frightening you could be frightening they could be frightening
Perfect
I could have frightened you could have frightened she 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 she 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 she 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 she 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 she 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 she 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 she frighten? could we frighten? could you frighten? could they frighten?
V-ing form
could I be frightening? could you be frightening? could she be frightening? could we be frightening? could you be frightening? could they be frightening?
Perfect
could I have frightened? could you have frightened? could she 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 she 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 she 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 she 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 she 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 she have been frightening? couldn't we have been frightening? couldn't you have been frightening? couldn't they have been frightening?