must preserve
Regular verb: preserve - preserved- preserved

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must preserve
you must preserve
she must preserve
we must preserve
you must preserve
they must preserve 	I must be preserving
you must be preserving
she must be preserving
we must be preserving
you must be preserving
they must be preserving	I must have preserved
you must have preserved
she must have preserved
we must have preserved
you must have preserved
they must have preserved	I must have been preserving
you must have been preserving
she must have been preserving
we must have been preserving
you must have been preserving
they must have been preserving	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't preserve
you mustn't preserve
she mustn't preserve
we mustn't preserve
you mustn't preserve
they mustn't preserve 	I mustn't be preserving
you mustn't be preserving
she mustn't be preserving
we mustn't be preserving
you mustn't be preserving
they mustn't be preserving	I mustn't have preserved
you mustn't have preserved
she mustn't have preserved
we mustn't have preserved
you mustn't have preserved
they mustn't have preserved	I mustn't have been preserving
you mustn't have been preserving
she mustn't have been preserving
we mustn't have been preserving
you mustn't have been preserving
they mustn't have been preserving	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I preserve?
must you preserve?
must she preserve?
must we preserve?
must you preserve?
must they preserve? 	must I be preserving?
must you be preserving?
must she be preserving?
must we be preserving?
must you be preserving?
must they be preserving? 	must I have preserved?
must you have preserved?
must she have preserved?
must we have preserved?
must you have preserved?
must they have preserved? 	must I have been preserving?
must you have been preserving?
must she have been preserving?
must we have been preserving?
must you have been preserving?
must they have been preserving? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I preserve?
mustn't you preserve?
mustn't she preserve?
mustn't we preserve?
mustn't you preserve?
mustn't they preserve? 	mustn't I be preserving?
mustn't you be preserving?
mustn't she be preserving?
mustn't we be preserving?
mustn't you be preserving?
mustn't they be preserving? 	mustn't I have preserved?
mustn't you have preserved?
mustn't she have preserved?
mustn't we have preserved?
mustn't you have preserved?
mustn't they have preserved? 	mustn't I have been preserving?
mustn't you have been preserving?
mustn't she have been preserving?
mustn't we have been preserving?
mustn't you have been preserving?
mustn't they have been preserving?