English verb conjugation
MUST GRIN

Regular verb: grin - grinned - grinned

Affirmation

Simple form	V-ing form
I must grin you must grin he must grin we must grin you must grin they must grin	I must be grinning you must be grinning he must be grinning we must be grinning you must be grinning they must be grinning
Perfect	V-ing perfect
I must have grinned you must have grinned he must have grinned we must have grinned you must have grinned they must have grinned	I must have been grinning you must have been grinning he must have been grinning we must have been grinning you must have been grinning they must have been grinning

Negation

Simple form	V-ing form
I mustn't grin you mustn't grin he mustn't grin we mustn't grin you mustn't grin they mustn't grin	I mustn't be grinning you mustn't be grinning he mustn't be grinning we mustn't be grinning you mustn't be grinning they mustn't be grinning
Perfect	V-ing perfect
I mustn't have grinned you mustn't have grinned he mustn't have grinned we mustn't have grinned you mustn't have grinned they mustn't have grinned	I mustn't have been grinning you mustn't have been grinning he mustn't have been grinning we mustn't have been grinning you mustn't have been grinning they mustn't have been grinning

Interrogative form

Simple form	V-ing form
must I grin? must you grin? must he grin? must we grin? must you grin? must they grin?	must I be grinning? must you be grinning? must he be grinning? must we be grinning? must you be grinning? must they be grinning?
Perfect	V-ing perfect
must I have grinned? must you have grinned? must he have grinned? must we have grinned? must you have grinned? must they have grinned?	must I have been grinning? must you have been grinning? must he have been grinning? must we have been grinning? must you have been grinning? must they have been grinning?

Interro-negative form

Simple form	V-ing form
mustn't I grin? mustn't you grin? mustn't he grin? mustn't we grin? mustn't you grin? mustn't they grin?	mustn't I be grinning? mustn't you be grinning? mustn't he be grinning? mustn't we be grinning? mustn't you be grinning? mustn't they be grinning?
Perfect	V-ing perfect
mustn't I have grinned? mustn't you have grinned? mustn't he have grinned? mustn't we have grinned? mustn't you have grinned? mustn't they have grinned?	mustn't I have been grinning? mustn't you have been grinning? mustn't he have been grinning? mustn't we have been grinning? mustn't you have been grinning? mustn't they have been grinning?