could preserve
Regular verb: preserve - preserved- preserved

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

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

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

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