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 must not mask you must not mask he must not mask we must not mask you must not mask they must not mask	I must not be masking you must not be masking he must not be masking we must not be masking you must not be masking they must not be masking
Perfect	V-ing perfect
I must not have masked you must not have masked he must not have masked we must not have masked you must not have masked they must not have masked	I must not have been masking you must not have been masking he must not have been masking we must not have been masking you must not have been masking they must not 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
must I not mask? must you not mask? must he not mask? must we not mask? must you not mask? must they not mask?	must I not be masking? must you not be masking? must he not be masking? must we not be masking? must you not be masking? must they not be masking?
Perfect	V-ing perfect
must I not have masked? must you not have masked? must he not have masked? must we not have masked? must you not have masked? must they not have masked?	must I not have been masking? must you not have been masking? must he not have been masking? must we not have been masking? must you not have been masking? must they not have been masking?