must knacker
Regular verb: knacker - knackered- knackered

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must knacker
you must knacker
he must knacker
we must knacker
you must knacker
they must knacker 	I must be knackering
you must be knackering
he must be knackering
we must be knackering
you must be knackering
they must be knackering	I must have knackered
you must have knackered
he must have knackered
we must have knackered
you must have knackered
they must have knackered	I must have been knackering
you must have been knackering
he must have been knackering
we must have been knackering
you must have been knackering
they must have been knackering	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't knacker
you mustn't knacker
he mustn't knacker
we mustn't knacker
you mustn't knacker
they mustn't knacker 	I mustn't be knackering
you mustn't be knackering
he mustn't be knackering
we mustn't be knackering
you mustn't be knackering
they mustn't be knackering	I mustn't have knackered
you mustn't have knackered
he mustn't have knackered
we mustn't have knackered
you mustn't have knackered
they mustn't have knackered	I mustn't have been knackering
you mustn't have been knackering
he mustn't have been knackering
we mustn't have been knackering
you mustn't have been knackering
they mustn't have been knackering	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I knacker?
must you knacker?
must he knacker?
must we knacker?
must you knacker?
must they knacker? 	must I be knackering?
must you be knackering?
must he be knackering?
must we be knackering?
must you be knackering?
must they be knackering? 	must I have knackered?
must you have knackered?
must he have knackered?
must we have knackered?
must you have knackered?
must they have knackered? 	must I have been knackering?
must you have been knackering?
must he have been knackering?
must we have been knackering?
must you have been knackering?
must they have been knackering? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I knacker?
mustn't you knacker?
mustn't he knacker?
mustn't we knacker?
mustn't you knacker?
mustn't they knacker? 	mustn't I be knackering?
mustn't you be knackering?
mustn't he be knackering?
mustn't we be knackering?
mustn't you be knackering?
mustn't they be knackering? 	mustn't I have knackered?
mustn't you have knackered?
mustn't he have knackered?
mustn't we have knackered?
mustn't you have knackered?
mustn't they have knackered? 	mustn't I have been knackering?
mustn't you have been knackering?
mustn't he have been knackering?
mustn't we have been knackering?
mustn't you have been knackering?
mustn't they have been knackering?