must befall
Irregular verb: befall - befell- befallen

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must befall
you must befall
he must befall
we must befall
you must befall
they must befall 	I must be befalling
you must be befalling
he must be befalling
we must be befalling
you must be befalling
they must be befalling	I must have befallen
you must have befallen
he must have befallen
we must have befallen
you must have befallen
they must have befallen	I must have been befalling
you must have been befalling
he must have been befalling
we must have been befalling
you must have been befalling
they must have been befalling	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't befall
you mustn't befall
he mustn't befall
we mustn't befall
you mustn't befall
they mustn't befall 	I mustn't be befalling
you mustn't be befalling
he mustn't be befalling
we mustn't be befalling
you mustn't be befalling
they mustn't be befalling	I mustn't have befallen
you mustn't have befallen
he mustn't have befallen
we mustn't have befallen
you mustn't have befallen
they mustn't have befallen	I mustn't have been befalling
you mustn't have been befalling
he mustn't have been befalling
we mustn't have been befalling
you mustn't have been befalling
they mustn't have been befalling	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I befall?
must you befall?
must he befall?
must we befall?
must you befall?
must they befall? 	must I be befalling?
must you be befalling?
must he be befalling?
must we be befalling?
must you be befalling?
must they be befalling? 	must I have befallen?
must you have befallen?
must he have befallen?
must we have befallen?
must you have befallen?
must they have befallen? 	must I have been befalling?
must you have been befalling?
must he have been befalling?
must we have been befalling?
must you have been befalling?
must they have been befalling? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I befall?
mustn't you befall?
mustn't he befall?
mustn't we befall?
mustn't you befall?
mustn't they befall? 	mustn't I be befalling?
mustn't you be befalling?
mustn't he be befalling?
mustn't we be befalling?
mustn't you be befalling?
mustn't they be befalling? 	mustn't I have befallen?
mustn't you have befallen?
mustn't he have befallen?
mustn't we have befallen?
mustn't you have befallen?
mustn't they have befallen? 	mustn't I have been befalling?
mustn't you have been befalling?
mustn't he have been befalling?
mustn't we have been befalling?
mustn't you have been befalling?
mustn't they have been befalling?