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