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