English verb conjugation
MUST BIRL

Regular verb: birl - birled - birled

Affirmation

Simple form	V-ing form
I must birl you must birl he must birl we must birl you must birl they must birl	I must be birling you must be birling he must be birling we must be birling you must be birling they must be birling
Perfect	V-ing perfect
I must have birled you must have birled he must have birled we must have birled you must have birled they must have birled	I must have been birling you must have been birling he must have been birling we must have been birling you must have been birling they must have been birling

Negation

Simple form	V-ing form
I mustn't birl you mustn't birl he mustn't birl we mustn't birl you mustn't birl they mustn't birl	I mustn't be birling you mustn't be birling he mustn't be birling we mustn't be birling you mustn't be birling they mustn't be birling
Perfect	V-ing perfect
I mustn't have birled you mustn't have birled he mustn't have birled we mustn't have birled you mustn't have birled they mustn't have birled	I mustn't have been birling you mustn't have been birling he mustn't have been birling we mustn't have been birling you mustn't have been birling they mustn't have been birling

Interrogative form

Simple form	V-ing form
must I birl? must you birl? must he birl? must we birl? must you birl? must they birl?	must I be birling? must you be birling? must he be birling? must we be birling? must you be birling? must they be birling?
Perfect	V-ing perfect
must I have birled? must you have birled? must he have birled? must we have birled? must you have birled? must they have birled?	must I have been birling? must you have been birling? must he have been birling? must we have been birling? must you have been birling? must they have been birling?

Interro-negative form

Simple form	V-ing form
mustn't I birl? mustn't you birl? mustn't he birl? mustn't we birl? mustn't you birl? mustn't they birl?	mustn't I be birling? mustn't you be birling? mustn't he be birling? mustn't we be birling? mustn't you be birling? mustn't they be birling?
Perfect	V-ing perfect
mustn't I have birled? mustn't you have birled? mustn't he have birled? mustn't we have birled? mustn't you have birled? mustn't they have birled?	mustn't I have been birling? mustn't you have been birling? mustn't he have been birling? mustn't we have been birling? mustn't you have been birling? mustn't they have been birling?