I could obstruct you could obstruct he could obstruct we could obstruct you could obstruct they could obstruct
V-ing form
I could be obstructing you could be obstructing he could be obstructing we could be obstructing you could be obstructing they could be obstructing
Perfect
I could have obstructed you could have obstructed he could have obstructed we could have obstructed you could have obstructed they could have obstructed
V-ing perfect
I could have been obstructing you could have been obstructing he could have been obstructing we could have been obstructing you could have been obstructing they could have been obstructing
Negation
Simple form
I could not obstruct you could not obstruct he could not obstruct we could not obstruct you could not obstruct they could not obstruct
V-ing form
I could not be obstructing you could not be obstructing he could not be obstructing we could not be obstructing you could not be obstructing they could not be obstructing
Perfect
I could not have obstructed you could not have obstructed he could not have obstructed we could not have obstructed you could not have obstructed they could not have obstructed
V-ing perfect
I could not have been obstructing you could not have been obstructing he could not have been obstructing we could not have been obstructing you could not have been obstructing they could not have been obstructing
Interrogative form
Simple form
could I obstruct? could you obstruct? could he obstruct? could we obstruct? could you obstruct? could they obstruct?
V-ing form
could I be obstructing? could you be obstructing? could he be obstructing? could we be obstructing? could you be obstructing? could they be obstructing?
Perfect
could I have obstructed? could you have obstructed? could he have obstructed? could we have obstructed? could you have obstructed? could they have obstructed?
V-ing perfect
could I have been obstructing? could you have been obstructing? could he have been obstructing? could we have been obstructing? could you have been obstructing? could they have been obstructing?
Interro-negative form
Simple form
could I not obstruct? could you not obstruct? could he not obstruct? could we not obstruct? could you not obstruct? could they not obstruct?
V-ing form
could I not be obstructing? could you not be obstructing? could he not be obstructing? could we not be obstructing? could you not be obstructing? could they not be obstructing?
Perfect
could I not have obstructed? could you not have obstructed? could he not have obstructed? could we not have obstructed? could you not have obstructed? could they not have obstructed?
V-ing perfect
could I not have been obstructing? could you not have been obstructing? could he not have been obstructing? could we not have been obstructing? could you not have been obstructing? could they not have been obstructing?