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