I could balloon you could balloon she could balloon we could balloon you could balloon they could balloon
V-ing form
I could be ballooning you could be ballooning she could be ballooning we could be ballooning you could be ballooning they could be ballooning
Perfect
I could have ballooned you could have ballooned she could have ballooned we could have ballooned you could have ballooned they could have ballooned
V-ing perfect
I could have been ballooning you could have been ballooning she could have been ballooning we could have been ballooning you could have been ballooning they could have been ballooning
Negation
Simple form
I could not balloon you could not balloon she could not balloon we could not balloon you could not balloon they could not balloon
V-ing form
I could not be ballooning you could not be ballooning she could not be ballooning we could not be ballooning you could not be ballooning they could not be ballooning
Perfect
I could not have ballooned you could not have ballooned she could not have ballooned we could not have ballooned you could not have ballooned they could not have ballooned
V-ing perfect
I could not have been ballooning you could not have been ballooning she could not have been ballooning we could not have been ballooning you could not have been ballooning they could not have been ballooning
Interrogative form
Simple form
could I balloon? could you balloon? could she balloon? could we balloon? could you balloon? could they balloon?
V-ing form
could I be ballooning? could you be ballooning? could she be ballooning? could we be ballooning? could you be ballooning? could they be ballooning?
Perfect
could I have ballooned? could you have ballooned? could she have ballooned? could we have ballooned? could you have ballooned? could they have ballooned?
V-ing perfect
could I have been ballooning? could you have been ballooning? could she have been ballooning? could we have been ballooning? could you have been ballooning? could they have been ballooning?
Interro-negative form
Simple form
could I not balloon? could you not balloon? could she not balloon? could we not balloon? could you not balloon? could they not balloon?
V-ing form
could I not be ballooning? could you not be ballooning? could she not be ballooning? could we not be ballooning? could you not be ballooning? could they not be ballooning?
Perfect
could I not have ballooned? could you not have ballooned? could she not have ballooned? could we not have ballooned? could you not have ballooned? could they not have ballooned?
V-ing perfect
could I not have been ballooning? could you not have been ballooning? could she not have been ballooning? could we not have been ballooning? could you not have been ballooning? could they not have been ballooning?