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