must prop
Regular verb: prop - propped- propped

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must prop
you must prop
he must prop
we must prop
you must prop
they must prop 	I must be propping
you must be propping
he must be propping
we must be propping
you must be propping
they must be propping	I must have propped
you must have propped
he must have propped
we must have propped
you must have propped
they must have propped	I must have been propping
you must have been propping
he must have been propping
we must have been propping
you must have been propping
they must have been propping	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't prop
you mustn't prop
he mustn't prop
we mustn't prop
you mustn't prop
they mustn't prop 	I mustn't be propping
you mustn't be propping
he mustn't be propping
we mustn't be propping
you mustn't be propping
they mustn't be propping	I mustn't have propped
you mustn't have propped
he mustn't have propped
we mustn't have propped
you mustn't have propped
they mustn't have propped	I mustn't have been propping
you mustn't have been propping
he mustn't have been propping
we mustn't have been propping
you mustn't have been propping
they mustn't have been propping	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I prop?
must you prop?
must he prop?
must we prop?
must you prop?
must they prop? 	must I be propping?
must you be propping?
must he be propping?
must we be propping?
must you be propping?
must they be propping? 	must I have propped?
must you have propped?
must he have propped?
must we have propped?
must you have propped?
must they have propped? 	must I have been propping?
must you have been propping?
must he have been propping?
must we have been propping?
must you have been propping?
must they have been propping? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I prop?
mustn't you prop?
mustn't he prop?
mustn't we prop?
mustn't you prop?
mustn't they prop? 	mustn't I be propping?
mustn't you be propping?
mustn't he be propping?
mustn't we be propping?
mustn't you be propping?
mustn't they be propping? 	mustn't I have propped?
mustn't you have propped?
mustn't he have propped?
mustn't we have propped?
mustn't you have propped?
mustn't they have propped? 	mustn't I have been propping?
mustn't you have been propping?
mustn't he have been propping?
mustn't we have been propping?
mustn't you have been propping?
mustn't they have been propping?