I must unmask you must unmask she must unmask we must unmask you must unmask they must unmask
V-ing form
I must be unmasking you must be unmasking she must be unmasking we must be unmasking you must be unmasking they must be unmasking
Perfect
I must have unmasked you must have unmasked she must have unmasked we must have unmasked you must have unmasked they must have unmasked
V-ing perfect
I must have been unmasking you must have been unmasking she must have been unmasking we must have been unmasking you must have been unmasking they must have been unmasking
Negation
Simple form
I must not unmask you must not unmask she must not unmask we must not unmask you must not unmask they must not unmask
V-ing form
I must not be unmasking you must not be unmasking she must not be unmasking we must not be unmasking you must not be unmasking they must not be unmasking
Perfect
I must not have unmasked you must not have unmasked she must not have unmasked we must not have unmasked you must not have unmasked they must not have unmasked
V-ing perfect
I must not have been unmasking you must not have been unmasking she must not have been unmasking we must not have been unmasking you must not have been unmasking they must not have been unmasking
Interrogative form
Simple form
must I unmask? must you unmask? must she unmask? must we unmask? must you unmask? must they unmask?
V-ing form
must I be unmasking? must you be unmasking? must she be unmasking? must we be unmasking? must you be unmasking? must they be unmasking?
Perfect
must I have unmasked? must you have unmasked? must she have unmasked? must we have unmasked? must you have unmasked? must they have unmasked?
V-ing perfect
must I have been unmasking? must you have been unmasking? must she have been unmasking? must we have been unmasking? must you have been unmasking? must they have been unmasking?
Interro-negative form
Simple form
must I not unmask? must you not unmask? must she not unmask? must we not unmask? must you not unmask? must they not unmask?
V-ing form
must I not be unmasking? must you not be unmasking? must she not be unmasking? must we not be unmasking? must you not be unmasking? must they not be unmasking?
Perfect
must I not have unmasked? must you not have unmasked? must she not have unmasked? must we not have unmasked? must you not have unmasked? must they not have unmasked?
V-ing perfect
must I not have been unmasking? must you not have been unmasking? must she not have been unmasking? must we not have been unmasking? must you not have been unmasking? must they not have been unmasking?