I must answer you must answer she must answer we must answer you must answer they must answer
V-ing form
I must be answering you must be answering she must be answering we must be answering you must be answering they must be answering
Perfect
I must have answered you must have answered she must have answered we must have answered you must have answered they must have answered
V-ing perfect
I must have been answering you must have been answering she must have been answering we must have been answering you must have been answering they must have been answering
Negation
Simple form
I mustn't answer you mustn't answer she mustn't answer we mustn't answer you mustn't answer they mustn't answer
V-ing form
I mustn't be answering you mustn't be answering she mustn't be answering we mustn't be answering you mustn't be answering they mustn't be answering
Perfect
I mustn't have answered you mustn't have answered she mustn't have answered we mustn't have answered you mustn't have answered they mustn't have answered
V-ing perfect
I mustn't have been answering you mustn't have been answering she mustn't have been answering we mustn't have been answering you mustn't have been answering they mustn't have been answering
Interrogative form
Simple form
must I answer? must you answer? must she answer? must we answer? must you answer? must they answer?
V-ing form
must I be answering? must you be answering? must she be answering? must we be answering? must you be answering? must they be answering?
Perfect
must I have answered? must you have answered? must she have answered? must we have answered? must you have answered? must they have answered?
V-ing perfect
must I have been answering? must you have been answering? must she have been answering? must we have been answering? must you have been answering? must they have been answering?
Interro-negative form
Simple form
mustn't I answer? mustn't you answer? mustn't she answer? mustn't we answer? mustn't you answer? mustn't they answer?
V-ing form
mustn't I be answering? mustn't you be answering? mustn't she be answering? mustn't we be answering? mustn't you be answering? mustn't they be answering?
Perfect
mustn't I have answered? mustn't you have answered? mustn't she have answered? mustn't we have answered? mustn't you have answered? mustn't they have answered?
V-ing perfect
mustn't I have been answering? mustn't you have been answering? mustn't she have been answering? mustn't we have been answering? mustn't you have been answering? mustn't they have been answering?