I must skin you must skin she must skin we must skin you must skin they must skin
V-ing form
I must be skinning you must be skinning she must be skinning we must be skinning you must be skinning they must be skinning
Perfect
I must have skinned you must have skinned she 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 she must have been skinning we must have been skinning you must have been skinning they must have been skinning
Negation
Simple form
I must not skin you must not skin she must not skin we must not skin you must not skin they must not skin
V-ing form
I must not be skinning you must not be skinning she must not be skinning we must not be skinning you must not be skinning they must not be skinning
Perfect
I must not have skinned you must not have skinned she must not have skinned we must not have skinned you must not have skinned they must not have skinned
V-ing perfect
I must not have been skinning you must not have been skinning she must not have been skinning we must not have been skinning you must not have been skinning they must not have been skinning
Interrogative form
Simple form
must I skin? must you skin? must she skin? must we skin? must you skin? must they skin?
V-ing form
must I be skinning? must you be skinning? must she be skinning? must we be skinning? must you be skinning? must they be skinning?
Perfect
must I have skinned? must you have skinned? must she 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 she have been skinning? must we have been skinning? must you have been skinning? must they have been skinning?
Interro-negative form
Simple form
must I not skin? must you not skin? must she not skin? must we not skin? must you not skin? must they not skin?
V-ing form
must I not be skinning? must you not be skinning? must she not be skinning? must we not be skinning? must you not be skinning? must they not be skinning?
Perfect
must I not have skinned? must you not have skinned? must she not have skinned? must we not have skinned? must you not have skinned? must they not have skinned?
V-ing perfect
must I not have been skinning? must you not have been skinning? must she not have been skinning? must we not have been skinning? must you not have been skinning? must they not have been skinning?