I must obscure you must obscure he must obscure we must obscure you must obscure they must obscure
V-ing form
I must be obscuring you must be obscuring he must be obscuring we must be obscuring you must be obscuring they must be obscuring
Perfect
I must have obscured you must have obscured he must have obscured we must have obscured you must have obscured they must have obscured
V-ing perfect
I must have been obscuring you must have been obscuring he must have been obscuring we must have been obscuring you must have been obscuring they must have been obscuring
Negation
Simple form
I mustn't obscure you mustn't obscure he mustn't obscure we mustn't obscure you mustn't obscure they mustn't obscure
V-ing form
I mustn't be obscuring you mustn't be obscuring he mustn't be obscuring we mustn't be obscuring you mustn't be obscuring they mustn't be obscuring
Perfect
I mustn't have obscured you mustn't have obscured he mustn't have obscured we mustn't have obscured you mustn't have obscured they mustn't have obscured
V-ing perfect
I mustn't have been obscuring you mustn't have been obscuring he mustn't have been obscuring we mustn't have been obscuring you mustn't have been obscuring they mustn't have been obscuring
Interrogative form
Simple form
must I obscure? must you obscure? must he obscure? must we obscure? must you obscure? must they obscure?
V-ing form
must I be obscuring? must you be obscuring? must he be obscuring? must we be obscuring? must you be obscuring? must they be obscuring?
Perfect
must I have obscured? must you have obscured? must he have obscured? must we have obscured? must you have obscured? must they have obscured?
V-ing perfect
must I have been obscuring? must you have been obscuring? must he have been obscuring? must we have been obscuring? must you have been obscuring? must they have been obscuring?
Interro-negative form
Simple form
mustn't I obscure? mustn't you obscure? mustn't he obscure? mustn't we obscure? mustn't you obscure? mustn't they obscure?
V-ing form
mustn't I be obscuring? mustn't you be obscuring? mustn't he be obscuring? mustn't we be obscuring? mustn't you be obscuring? mustn't they be obscuring?
Perfect
mustn't I have obscured? mustn't you have obscured? mustn't he have obscured? mustn't we have obscured? mustn't you have obscured? mustn't they have obscured?
V-ing perfect
mustn't I have been obscuring? mustn't you have been obscuring? mustn't he have been obscuring? mustn't we have been obscuring? mustn't you have been obscuring? mustn't they have been obscuring?