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 must not birl you must not birl he must not birl we must not birl you must not birl they must not birl	I must not be birling you must not be birling he must not be birling we must not be birling you must not be birling they must not be birling
Perfect	V-ing perfect
I must not have birled you must not have birled he must not have birled we must not have birled you must not have birled they must not have birled	I must not have been birling you must not have been birling he must not have been birling we must not have been birling you must not have been birling they must not 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
must I not birl? must you not birl? must he not birl? must we not birl? must you not birl? must they not birl?	must I not be birling? must you not be birling? must he not be birling? must we not be birling? must you not be birling? must they not be birling?
Perfect	V-ing perfect
must I not have birled? must you not have birled? must he not have birled? must we not have birled? must you not have birled? must they not have birled?	must I not have been birling? must you not have been birling? must he not have been birling? must we not have been birling? must you not have been birling? must they not have been birling?