English verb conjugation
MUST YAK

Regular verb: yak - yaked - yaked

Affirmation

Simple form	V-ing form
I must yak you must yak he must yak we must yak you must yak they must yak	I must be yaking you must be yaking he must be yaking we must be yaking you must be yaking they must be yaking
Perfect	V-ing perfect
I must have yaked you must have yaked he must have yaked we must have yaked you must have yaked they must have yaked	I must have been yaking you must have been yaking he must have been yaking we must have been yaking you must have been yaking they must have been yaking

Negation

Simple form	V-ing form
I mustn't yak you mustn't yak he mustn't yak we mustn't yak you mustn't yak they mustn't yak	I mustn't be yaking you mustn't be yaking he mustn't be yaking we mustn't be yaking you mustn't be yaking they mustn't be yaking
Perfect	V-ing perfect
I mustn't have yaked you mustn't have yaked he mustn't have yaked we mustn't have yaked you mustn't have yaked they mustn't have yaked	I mustn't have been yaking you mustn't have been yaking he mustn't have been yaking we mustn't have been yaking you mustn't have been yaking they mustn't have been yaking

Interrogative form

Simple form	V-ing form
must I yak? must you yak? must he yak? must we yak? must you yak? must they yak?	must I be yaking? must you be yaking? must he be yaking? must we be yaking? must you be yaking? must they be yaking?
Perfect	V-ing perfect
must I have yaked? must you have yaked? must he have yaked? must we have yaked? must you have yaked? must they have yaked?	must I have been yaking? must you have been yaking? must he have been yaking? must we have been yaking? must you have been yaking? must they have been yaking?

Interro-negative form

Simple form	V-ing form
mustn't I yak? mustn't you yak? mustn't he yak? mustn't we yak? mustn't you yak? mustn't they yak?	mustn't I be yaking? mustn't you be yaking? mustn't he be yaking? mustn't we be yaking? mustn't you be yaking? mustn't they be yaking?
Perfect	V-ing perfect
mustn't I have yaked? mustn't you have yaked? mustn't he have yaked? mustn't we have yaked? mustn't you have yaked? mustn't they have yaked?	mustn't I have been yaking? mustn't you have been yaking? mustn't he have been yaking? mustn't we have been yaking? mustn't you have been yaking? mustn't they have been yaking?