English verb conjugation
MUST YAK

Regular verb: yak - yaked - yaked

Affirmation

Simple form	V-ing form
I must yak you must yak she must yak we must yak you must yak they must yak	I must be yaking you must be yaking she 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 she 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 she 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 she 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 she 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 she 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 she 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 she yak? must we yak? must you yak? must they yak?	must I be yaking? must you be yaking? must she 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 she 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 she 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 she 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 she 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 she 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 she have been yaking? mustn't we have been yaking? mustn't you have been yaking? mustn't they have been yaking?