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