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