English verb conjugation
CAN EXIST

Regular verb: exist - existed - existed

Affirmation

Simple form	V-ing form
I can exist you can exist she can exist we can exist you can exist they can exist	I can be existing you can be existing she can be existing we can be existing you can be existing they can be existing
Perfect	V-ing perfect
I can have existed you can have existed she can have existed we can have existed you can have existed they can have existed	I can have been existing you can have been existing she can have been existing we can have been existing you can have been existing they can have been existing

Negation

Simple form	V-ing form
I cannot exist you cannot exist she cannot exist we cannot exist you cannot exist they cannot exist	I cannot be existing you cannot be existing she cannot be existing we cannot be existing you cannot be existing they cannot be existing
Perfect	V-ing perfect
I cannot have existed you cannot have existed she cannot have existed we cannot have existed you cannot have existed they cannot have existed	I cannot have been existing you cannot have been existing she cannot have been existing we cannot have been existing you cannot have been existing they cannot have been existing

Interrogative form

Simple form	V-ing form
can I exist? can you exist? can she exist? can we exist? can you exist? can they exist?	can I be existing? can you be existing? can she be existing? can we be existing? can you be existing? can they be existing?
Perfect	V-ing perfect
can I have existed? can you have existed? can she have existed? can we have existed? can you have existed? can they have existed?	can I have been existing? can you have been existing? can she have been existing? can we have been existing? can you have been existing? can they have been existing?

Interro-negative form

Simple form	V-ing form
can I not exist? can you not exist? can she not exist? can we not exist? can you not exist? can they not exist?	can I not be existing? can you not be existing? can she not be existing? can we not be existing? can you not be existing? can they not be existing?
Perfect	V-ing perfect
can I not have existed? can you not have existed? can she not have existed? can we not have existed? can you not have existed? can they not have existed?	can I not have been existing? can you not have been existing? can she not have been existing? can we not have been existing? can you not have been existing? can they not have been existing?