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