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