I could calender you could calender she could calender we could calender you could calender they could calender
V-ing form
I could be calendering you could be calendering she could be calendering we could be calendering you could be calendering they could be calendering
Perfect
I could have calendered you could have calendered she 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 she 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 she 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 she 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 she 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 she 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 she calender? could we calender? could you calender? could they calender?
V-ing form
could I be calendering? could you be calendering? could she be calendering? could we be calendering? could you be calendering? could they be calendering?
Perfect
could I have calendered? could you have calendered? could she 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 she 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 she 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 she 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 she 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 she have been calendering? couldn't we have been calendering? couldn't you have been calendering? couldn't they have been calendering?