I must obstruct you must obstruct she must obstruct we must obstruct you must obstruct they must obstruct
V-ing form
I must be obstructing you must be obstructing she must be obstructing we must be obstructing you must be obstructing they must be obstructing
Perfect
I must have obstructed you must have obstructed she must have obstructed we must have obstructed you must have obstructed they must have obstructed
V-ing perfect
I must have been obstructing you must have been obstructing she must have been obstructing we must have been obstructing you must have been obstructing they must have been obstructing
Negation
Simple form
I mustn't obstruct you mustn't obstruct she mustn't obstruct we mustn't obstruct you mustn't obstruct they mustn't obstruct
V-ing form
I mustn't be obstructing you mustn't be obstructing she mustn't be obstructing we mustn't be obstructing you mustn't be obstructing they mustn't be obstructing
Perfect
I mustn't have obstructed you mustn't have obstructed she mustn't have obstructed we mustn't have obstructed you mustn't have obstructed they mustn't have obstructed
V-ing perfect
I mustn't have been obstructing you mustn't have been obstructing she mustn't have been obstructing we mustn't have been obstructing you mustn't have been obstructing they mustn't have been obstructing
Interrogative form
Simple form
must I obstruct? must you obstruct? must she obstruct? must we obstruct? must you obstruct? must they obstruct?
V-ing form
must I be obstructing? must you be obstructing? must she be obstructing? must we be obstructing? must you be obstructing? must they be obstructing?
Perfect
must I have obstructed? must you have obstructed? must she have obstructed? must we have obstructed? must you have obstructed? must they have obstructed?
V-ing perfect
must I have been obstructing? must you have been obstructing? must she have been obstructing? must we have been obstructing? must you have been obstructing? must they have been obstructing?
Interro-negative form
Simple form
mustn't I obstruct? mustn't you obstruct? mustn't she obstruct? mustn't we obstruct? mustn't you obstruct? mustn't they obstruct?
V-ing form
mustn't I be obstructing? mustn't you be obstructing? mustn't she be obstructing? mustn't we be obstructing? mustn't you be obstructing? mustn't they be obstructing?
Perfect
mustn't I have obstructed? mustn't you have obstructed? mustn't she have obstructed? mustn't we have obstructed? mustn't you have obstructed? mustn't they have obstructed?
V-ing perfect
mustn't I have been obstructing? mustn't you have been obstructing? mustn't she have been obstructing? mustn't we have been obstructing? mustn't you have been obstructing? mustn't they have been obstructing?