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