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