I could collect you could collect she could collect we could collect you could collect they could collect
V-ing form
I could be collecting you could be collecting she could be collecting we could be collecting you could be collecting they could be collecting
Perfect
I could have collected you could have collected she could have collected we could have collected you could have collected they could have collected
V-ing perfect
I could have been collecting you could have been collecting she could have been collecting we could have been collecting you could have been collecting they could have been collecting
Negation
Simple form
I could not collect you could not collect she could not collect we could not collect you could not collect they could not collect
V-ing form
I could not be collecting you could not be collecting she could not be collecting we could not be collecting you could not be collecting they could not be collecting
Perfect
I could not have collected you could not have collected she could not have collected we could not have collected you could not have collected they could not have collected
V-ing perfect
I could not have been collecting you could not have been collecting she could not have been collecting we could not have been collecting you could not have been collecting they could not have been collecting
Interrogative form
Simple form
could I collect? could you collect? could she collect? could we collect? could you collect? could they collect?
V-ing form
could I be collecting? could you be collecting? could she be collecting? could we be collecting? could you be collecting? could they be collecting?
Perfect
could I have collected? could you have collected? could she have collected? could we have collected? could you have collected? could they have collected?
V-ing perfect
could I have been collecting? could you have been collecting? could she have been collecting? could we have been collecting? could you have been collecting? could they have been collecting?
Interro-negative form
Simple form
could I not collect? could you not collect? could she not collect? could we not collect? could you not collect? could they not collect?
V-ing form
could I not be collecting? could you not be collecting? could she not be collecting? could we not be collecting? could you not be collecting? could they not be collecting?
Perfect
could I not have collected? could you not have collected? could she not have collected? could we not have collected? could you not have collected? could they not have collected?
V-ing perfect
could I not have been collecting? could you not have been collecting? could she not have been collecting? could we not have been collecting? could you not have been collecting? could they not have been collecting?