English verb conjugation
MUST MASK

Regular verb: mask - masked - masked

Affirmation

Simple form	V-ing form
I must mask you must mask he must mask we must mask you must mask they must mask	I must be masking you must be masking he must be masking we must be masking you must be masking they must be masking
Perfect	V-ing perfect
I must have masked you must have masked he must have masked we must have masked you must have masked they must have masked	I must have been masking you must have been masking he must have been masking we must have been masking you must have been masking they must have been masking

Negation

Simple form	V-ing form
I mustn't mask you mustn't mask he mustn't mask we mustn't mask you mustn't mask they mustn't mask	I mustn't be masking you mustn't be masking he mustn't be masking we mustn't be masking you mustn't be masking they mustn't be masking
Perfect	V-ing perfect
I mustn't have masked you mustn't have masked he mustn't have masked we mustn't have masked you mustn't have masked they mustn't have masked	I mustn't have been masking you mustn't have been masking he mustn't have been masking we mustn't have been masking you mustn't have been masking they mustn't have been masking

Interrogative form

Simple form	V-ing form
must I mask? must you mask? must he mask? must we mask? must you mask? must they mask?	must I be masking? must you be masking? must he be masking? must we be masking? must you be masking? must they be masking?
Perfect	V-ing perfect
must I have masked? must you have masked? must he have masked? must we have masked? must you have masked? must they have masked?	must I have been masking? must you have been masking? must he have been masking? must we have been masking? must you have been masking? must they have been masking?

Interro-negative form

Simple form	V-ing form
mustn't I mask? mustn't you mask? mustn't he mask? mustn't we mask? mustn't you mask? mustn't they mask?	mustn't I be masking? mustn't you be masking? mustn't he be masking? mustn't we be masking? mustn't you be masking? mustn't they be masking?
Perfect	V-ing perfect
mustn't I have masked? mustn't you have masked? mustn't he have masked? mustn't we have masked? mustn't you have masked? mustn't they have masked?	mustn't I have been masking? mustn't you have been masking? mustn't he have been masking? mustn't we have been masking? mustn't you have been masking? mustn't they have been masking?