English verb conjugation
COULD OCCUR

Regular verb: occur - occurred - occurred

Affirmation

Simple form	V-ing form
I could occur you could occur she could occur we could occur you could occur they could occur	I could be occurring you could be occurring she could be occurring we could be occurring you could be occurring they could be occurring
Perfect	V-ing perfect
I could have occurred you could have occurred she could have occurred we could have occurred you could have occurred they could have occurred	I could have been occurring you could have been occurring she could have been occurring we could have been occurring you could have been occurring they could have been occurring

Negation

Simple form	V-ing form
I couldn't occur you couldn't occur she couldn't occur we couldn't occur you couldn't occur they couldn't occur	I couldn't be occurring you couldn't be occurring she couldn't be occurring we couldn't be occurring you couldn't be occurring they couldn't be occurring
Perfect	V-ing perfect
I couldn't have occurred you couldn't have occurred she couldn't have occurred we couldn't have occurred you couldn't have occurred they couldn't have occurred	I couldn't have been occurring you couldn't have been occurring she couldn't have been occurring we couldn't have been occurring you couldn't have been occurring they couldn't have been occurring

Interrogative form

Simple form	V-ing form
could I occur? could you occur? could she occur? could we occur? could you occur? could they occur?	could I be occurring? could you be occurring? could she be occurring? could we be occurring? could you be occurring? could they be occurring?
Perfect	V-ing perfect
could I have occurred? could you have occurred? could she have occurred? could we have occurred? could you have occurred? could they have occurred?	could I have been occurring? could you have been occurring? could she have been occurring? could we have been occurring? could you have been occurring? could they have been occurring?

Interro-negative form

Simple form	V-ing form
couldn't I occur? couldn't you occur? couldn't she occur? couldn't we occur? couldn't you occur? couldn't they occur?	couldn't I be occurring? couldn't you be occurring? couldn't she be occurring? couldn't we be occurring? couldn't you be occurring? couldn't they be occurring?
Perfect	V-ing perfect
couldn't I have occurred? couldn't you have occurred? couldn't she have occurred? couldn't we have occurred? couldn't you have occurred? couldn't they have occurred?	couldn't I have been occurring? couldn't you have been occurring? couldn't she have been occurring? couldn't we have been occurring? couldn't you have been occurring? couldn't they have been occurring?