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