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