English verb conjugation
CAN MODIFY

Regular verb: modify - modified - modified

Affirmation

Simple form	V-ing form
I can modify you can modify she can modify we can modify you can modify they can modify	I can be modifying you can be modifying she can be modifying we can be modifying you can be modifying they can be modifying
Perfect	V-ing perfect
I can have modified you can have modified she can have modified we can have modified you can have modified they can have modified	I can have been modifying you can have been modifying she can have been modifying we can have been modifying you can have been modifying they can have been modifying

Negation

Simple form	V-ing form
I cannot modify you cannot modify she cannot modify we cannot modify you cannot modify they cannot modify	I cannot be modifying you cannot be modifying she cannot be modifying we cannot be modifying you cannot be modifying they cannot be modifying
Perfect	V-ing perfect
I cannot have modified you cannot have modified she cannot have modified we cannot have modified you cannot have modified they cannot have modified	I cannot have been modifying you cannot have been modifying she cannot have been modifying we cannot have been modifying you cannot have been modifying they cannot have been modifying

Interrogative form

Simple form	V-ing form
can I modify? can you modify? can she modify? can we modify? can you modify? can they modify?	can I be modifying? can you be modifying? can she be modifying? can we be modifying? can you be modifying? can they be modifying?
Perfect	V-ing perfect
can I have modified? can you have modified? can she have modified? can we have modified? can you have modified? can they have modified?	can I have been modifying? can you have been modifying? can she have been modifying? can we have been modifying? can you have been modifying? can they have been modifying?

Interro-negative form

Simple form	V-ing form
can I not modify? can you not modify? can she not modify? can we not modify? can you not modify? can they not modify?	can I not be modifying? can you not be modifying? can she not be modifying? can we not be modifying? can you not be modifying? can they not be modifying?
Perfect	V-ing perfect
can I not have modified? can you not have modified? can she not have modified? can we not have modified? can you not have modified? can they not have modified?	can I not have been modifying? can you not have been modifying? can she not have been modifying? can we not have been modifying? can you not have been modifying? can they not have been modifying?