I must shorten you must shorten he must shorten we must shorten you must shorten they must shorten
V-ing form
I must be shortening you must be shortening he must be shortening we must be shortening you must be shortening they must be shortening
Perfect
I must have shortened you must have shortened he 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 he must have been shortening we must have been shortening you must have been shortening they must have been shortening
Negation
Simple form
I must not shorten you must not shorten he must not shorten we must not shorten you must not shorten they must not shorten
V-ing form
I must not be shortening you must not be shortening he must not be shortening we must not be shortening you must not be shortening they must not be shortening
Perfect
I must not have shortened you must not have shortened he must not have shortened we must not have shortened you must not have shortened they must not have shortened
V-ing perfect
I must not have been shortening you must not have been shortening he must not have been shortening we must not have been shortening you must not have been shortening they must not have been shortening
Interrogative form
Simple form
must I shorten? must you shorten? must he shorten? must we shorten? must you shorten? must they shorten?
V-ing form
must I be shortening? must you be shortening? must he be shortening? must we be shortening? must you be shortening? must they be shortening?
Perfect
must I have shortened? must you have shortened? must he 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 he have been shortening? must we have been shortening? must you have been shortening? must they have been shortening?
Interro-negative form
Simple form
must I not shorten? must you not shorten? must he not shorten? must we not shorten? must you not shorten? must they not shorten?
V-ing form
must I not be shortening? must you not be shortening? must he not be shortening? must we not be shortening? must you not be shortening? must they not be shortening?
Perfect
must I not have shortened? must you not have shortened? must he not have shortened? must we not have shortened? must you not have shortened? must they not have shortened?
V-ing perfect
must I not have been shortening? must you not have been shortening? must he not have been shortening? must we not have been shortening? must you not have been shortening? must they not have been shortening?