I could calendar you could calendar she could calendar we could calendar you could calendar they could calendar
V-ing form
I could be calendaring you could be calendaring she could be calendaring we could be calendaring you could be calendaring they could be calendaring
Perfect
I could have calendared you could have calendared she could have calendared we could have calendared you could have calendared they could have calendared
V-ing perfect
I could have been calendaring you could have been calendaring she could have been calendaring we could have been calendaring you could have been calendaring they could have been calendaring
Negation
Simple form
I couldn't calendar you couldn't calendar she couldn't calendar we couldn't calendar you couldn't calendar they couldn't calendar
V-ing form
I couldn't be calendaring you couldn't be calendaring she couldn't be calendaring we couldn't be calendaring you couldn't be calendaring they couldn't be calendaring
Perfect
I couldn't have calendared you couldn't have calendared she couldn't have calendared we couldn't have calendared you couldn't have calendared they couldn't have calendared
V-ing perfect
I couldn't have been calendaring you couldn't have been calendaring she couldn't have been calendaring we couldn't have been calendaring you couldn't have been calendaring they couldn't have been calendaring
Interrogative form
Simple form
could I calendar? could you calendar? could she calendar? could we calendar? could you calendar? could they calendar?
V-ing form
could I be calendaring? could you be calendaring? could she be calendaring? could we be calendaring? could you be calendaring? could they be calendaring?
Perfect
could I have calendared? could you have calendared? could she have calendared? could we have calendared? could you have calendared? could they have calendared?
V-ing perfect
could I have been calendaring? could you have been calendaring? could she have been calendaring? could we have been calendaring? could you have been calendaring? could they have been calendaring?
Interro-negative form
Simple form
couldn't I calendar? couldn't you calendar? couldn't she calendar? couldn't we calendar? couldn't you calendar? couldn't they calendar?
V-ing form
couldn't I be calendaring? couldn't you be calendaring? couldn't she be calendaring? couldn't we be calendaring? couldn't you be calendaring? couldn't they be calendaring?
Perfect
couldn't I have calendared? couldn't you have calendared? couldn't she have calendared? couldn't we have calendared? couldn't you have calendared? couldn't they have calendared?
V-ing perfect
couldn't I have been calendaring? couldn't you have been calendaring? couldn't she have been calendaring? couldn't we have been calendaring? couldn't you have been calendaring? couldn't they have been calendaring?