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