must underlie
Irregular verb: underlie - underlay- underlain

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must underlie
you must underlie
she must underlie
we must underlie
you must underlie
they must underlie 	I must be underlying
you must be underlying
she must be underlying
we must be underlying
you must be underlying
they must be underlying	I must have underlain
you must have underlain
she must have underlain
we must have underlain
you must have underlain
they must have underlain	I must have been underlying
you must have been underlying
she must have been underlying
we must have been underlying
you must have been underlying
they must have been underlying	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't underlie
you mustn't underlie
she mustn't underlie
we mustn't underlie
you mustn't underlie
they mustn't underlie 	I mustn't be underlying
you mustn't be underlying
she mustn't be underlying
we mustn't be underlying
you mustn't be underlying
they mustn't be underlying	I mustn't have underlain
you mustn't have underlain
she mustn't have underlain
we mustn't have underlain
you mustn't have underlain
they mustn't have underlain	I mustn't have been underlying
you mustn't have been underlying
she mustn't have been underlying
we mustn't have been underlying
you mustn't have been underlying
they mustn't have been underlying	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I underlie?
must you underlie?
must she underlie?
must we underlie?
must you underlie?
must they underlie? 	must I be underlying?
must you be underlying?
must she be underlying?
must we be underlying?
must you be underlying?
must they be underlying? 	must I have underlain?
must you have underlain?
must she have underlain?
must we have underlain?
must you have underlain?
must they have underlain? 	must I have been underlying?
must you have been underlying?
must she have been underlying?
must we have been underlying?
must you have been underlying?
must they have been underlying? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I underlie?
mustn't you underlie?
mustn't she underlie?
mustn't we underlie?
mustn't you underlie?
mustn't they underlie? 	mustn't I be underlying?
mustn't you be underlying?
mustn't she be underlying?
mustn't we be underlying?
mustn't you be underlying?
mustn't they be underlying? 	mustn't I have underlain?
mustn't you have underlain?
mustn't she have underlain?
mustn't we have underlain?
mustn't you have underlain?
mustn't they have underlain? 	mustn't I have been underlying?
mustn't you have been underlying?
mustn't she have been underlying?
mustn't we have been underlying?
mustn't you have been underlying?
mustn't they have been underlying?