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