I could occur you could occur he could occur we could occur you could occur they could occur
Forma com V-ing
I could be occurring you could be occurring he could be occurring we could be occurring you could be occurring they could be occurring
Perfeito
I could have occurred you could have occurred he could have occurred we could have occurred you could have occurred they could have occurred
Perfeito com V-ing
I could have been occurring you could have been occurring he could have been occurring we could have been occurring you could have been occurring they could have been occurring
Negação
Forma simple
I couldn't occur you couldn't occur he couldn't occur we couldn't occur you couldn't occur they couldn't occur
Forma com V-ing
I couldn't be occurring you couldn't be occurring he couldn't be occurring we couldn't be occurring you couldn't be occurring they couldn't be occurring
Perfeito
I couldn't have occurred you couldn't have occurred he couldn't have occurred we couldn't have occurred you couldn't have occurred they couldn't have occurred
Perfeito com V-ing
I couldn't have been occurring you couldn't have been occurring he couldn't have been occurring we couldn't have been occurring you couldn't have been occurring they couldn't have been occurring
Forma interrogativa
Forma simple
could I occur? could you occur? could he occur? could we occur? could you occur? could they occur?
Forma com V-ing
could I be occurring? could you be occurring? could he be occurring? could we be occurring? could you be occurring? could they be occurring?
Perfeito
could I have occurred? could you have occurred? could he have occurred? could we have occurred? could you have occurred? could they have occurred?
Perfeito com V-ing
could I have been occurring? could you have been occurring? could he have been occurring? could we have been occurring? could you have been occurring? could they have been occurring?
Forma interro-Negação
Forma simple
couldn't I occur? couldn't you occur? couldn't he occur? couldn't we occur? couldn't you occur? couldn't they occur?
Forma com V-ing
couldn't I be occurring? couldn't you be occurring? couldn't he be occurring? couldn't we be occurring? couldn't you be occurring? couldn't they be occurring?
Perfeito
couldn't I have occurred? couldn't you have occurred? couldn't he have occurred? couldn't we have occurred? couldn't you have occurred? couldn't they have occurred?
Perfeito com V-ing
couldn't I have been occurring? couldn't you have been occurring? couldn't he have been occurring? couldn't we have been occurring? couldn't you have been occurring? couldn't they have been occurring?