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