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