I must discard you must discard he must discard we must discard you must discard they must discard
V-ing form
I must be discarding you must be discarding he must be discarding we must be discarding you must be discarding they must be discarding
Perfect
I must have discarded you must have discarded he must have discarded we must have discarded you must have discarded they must have discarded
V-ing perfect
I must have been discarding you must have been discarding he must have been discarding we must have been discarding you must have been discarding they must have been discarding
Negation
Simple form
I mustn't discard you mustn't discard he mustn't discard we mustn't discard you mustn't discard they mustn't discard
V-ing form
I mustn't be discarding you mustn't be discarding he mustn't be discarding we mustn't be discarding you mustn't be discarding they mustn't be discarding
Perfect
I mustn't have discarded you mustn't have discarded he mustn't have discarded we mustn't have discarded you mustn't have discarded they mustn't have discarded
V-ing perfect
I mustn't have been discarding you mustn't have been discarding he mustn't have been discarding we mustn't have been discarding you mustn't have been discarding they mustn't have been discarding
Interrogative form
Simple form
must I discard? must you discard? must he discard? must we discard? must you discard? must they discard?
V-ing form
must I be discarding? must you be discarding? must he be discarding? must we be discarding? must you be discarding? must they be discarding?
Perfect
must I have discarded? must you have discarded? must he have discarded? must we have discarded? must you have discarded? must they have discarded?
V-ing perfect
must I have been discarding? must you have been discarding? must he have been discarding? must we have been discarding? must you have been discarding? must they have been discarding?
Interro-negative form
Simple form
mustn't I discard? mustn't you discard? mustn't he discard? mustn't we discard? mustn't you discard? mustn't they discard?
V-ing form
mustn't I be discarding? mustn't you be discarding? mustn't he be discarding? mustn't we be discarding? mustn't you be discarding? mustn't they be discarding?
Perfect
mustn't I have discarded? mustn't you have discarded? mustn't he have discarded? mustn't we have discarded? mustn't you have discarded? mustn't they have discarded?
V-ing perfect
mustn't I have been discarding? mustn't you have been discarding? mustn't he have been discarding? mustn't we have been discarding? mustn't you have been discarding? mustn't they have been discarding?