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