I must stair-step you must stair-step he must stair-step we must stair-step you must stair-step they must stair-step
V-ing form
I must be stair-steping you must be stair-steping he must be stair-steping we must be stair-steping you must be stair-steping they must be stair-steping
Perfect
I must have stair-steped you must have stair-steped he must have stair-steped we must have stair-steped you must have stair-steped they must have stair-steped
V-ing perfect
I must have been stair-steping you must have been stair-steping he must have been stair-steping we must have been stair-steping you must have been stair-steping they must have been stair-steping
Negation
Simple form
I mustn't stair-step you mustn't stair-step he mustn't stair-step we mustn't stair-step you mustn't stair-step they mustn't stair-step
V-ing form
I mustn't be stair-steping you mustn't be stair-steping he mustn't be stair-steping we mustn't be stair-steping you mustn't be stair-steping they mustn't be stair-steping
Perfect
I mustn't have stair-steped you mustn't have stair-steped he mustn't have stair-steped we mustn't have stair-steped you mustn't have stair-steped they mustn't have stair-steped
V-ing perfect
I mustn't have been stair-steping you mustn't have been stair-steping he mustn't have been stair-steping we mustn't have been stair-steping you mustn't have been stair-steping they mustn't have been stair-steping
Interrogative form
Simple form
must I stair-step? must you stair-step? must he stair-step? must we stair-step? must you stair-step? must they stair-step?
V-ing form
must I be stair-steping? must you be stair-steping? must he be stair-steping? must we be stair-steping? must you be stair-steping? must they be stair-steping?
Perfect
must I have stair-steped? must you have stair-steped? must he have stair-steped? must we have stair-steped? must you have stair-steped? must they have stair-steped?
V-ing perfect
must I have been stair-steping? must you have been stair-steping? must he have been stair-steping? must we have been stair-steping? must you have been stair-steping? must they have been stair-steping?
Interro-negative form
Simple form
mustn't I stair-step? mustn't you stair-step? mustn't he stair-step? mustn't we stair-step? mustn't you stair-step? mustn't they stair-step?
V-ing form
mustn't I be stair-steping? mustn't you be stair-steping? mustn't he be stair-steping? mustn't we be stair-steping? mustn't you be stair-steping? mustn't they be stair-steping?
Perfect
mustn't I have stair-steped? mustn't you have stair-steped? mustn't he have stair-steped? mustn't we have stair-steped? mustn't you have stair-steped? mustn't they have stair-steped?
V-ing perfect
mustn't I have been stair-steping? mustn't you have been stair-steping? mustn't he have been stair-steping? mustn't we have been stair-steping? mustn't you have been stair-steping? mustn't they have been stair-steping?