English verb conjugation
CAN EXIST

Regular verb: exist - existed - existed

Affirmation

Simple form	V-ing form
I can exist you can exist he can exist we can exist you can exist they can exist	I can be existing you can be existing he 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 he 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 he 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 can't exist you can't exist he can't exist we can't exist you can't exist they can't exist	I can't be existing you can't be existing he can't be existing we can't be existing you can't be existing they can't be existing
Perfect	V-ing perfect
I can't have existed you can't have existed he can't have existed we can't have existed you can't have existed they can't have existed	I can't have been existing you can't have been existing he can't have been existing we can't have been existing you can't have been existing they can't have been existing

Interrogative form

Simple form	V-ing form
can I exist? can you exist? can he exist? can we exist? can you exist? can they exist?	can I be existing? can you be existing? can he 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 he 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 he 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't I exist? can't you exist? can't he exist? can't we exist? can't you exist? can't they exist?	can't I be existing? can't you be existing? can't he be existing? can't we be existing? can't you be existing? can't they be existing?
Perfect	V-ing perfect
can't I have existed? can't you have existed? can't he have existed? can't we have existed? can't you have existed? can't they have existed?	can't I have been existing? can't you have been existing? can't he have been existing? can't we have been existing? can't you have been existing? can't they have been existing?