I must chat you must chat she must chat we must chat you must chat they must chat
V-ing form
I must be chatting you must be chatting she must be chatting we must be chatting you must be chatting they must be chatting
Perfect
I must have chatted you must have chatted she must have chatted we must have chatted you must have chatted they must have chatted
V-ing perfect
I must have been chatting you must have been chatting she must have been chatting we must have been chatting you must have been chatting they must have been chatting
Negation
Simple form
I must not chat you must not chat she must not chat we must not chat you must not chat they must not chat
V-ing form
I must not be chatting you must not be chatting she must not be chatting we must not be chatting you must not be chatting they must not be chatting
Perfect
I must not have chatted you must not have chatted she must not have chatted we must not have chatted you must not have chatted they must not have chatted
V-ing perfect
I must not have been chatting you must not have been chatting she must not have been chatting we must not have been chatting you must not have been chatting they must not have been chatting
Interrogative form
Simple form
must I chat? must you chat? must she chat? must we chat? must you chat? must they chat?
V-ing form
must I be chatting? must you be chatting? must she be chatting? must we be chatting? must you be chatting? must they be chatting?
Perfect
must I have chatted? must you have chatted? must she have chatted? must we have chatted? must you have chatted? must they have chatted?
V-ing perfect
must I have been chatting? must you have been chatting? must she have been chatting? must we have been chatting? must you have been chatting? must they have been chatting?
Interro-negative form
Simple form
must I not chat? must you not chat? must she not chat? must we not chat? must you not chat? must they not chat?
V-ing form
must I not be chatting? must you not be chatting? must she not be chatting? must we not be chatting? must you not be chatting? must they not be chatting?
Perfect
must I not have chatted? must you not have chatted? must she not have chatted? must we not have chatted? must you not have chatted? must they not have chatted?
V-ing perfect
must I not have been chatting? must you not have been chatting? must she not have been chatting? must we not have been chatting? must you not have been chatting? must they not have been chatting?