English verb conjugation
CAN REF

Regular verb: ref - refed - refed

Affirmation

Simple form	V-ing form
I can ref you can ref she can ref we can ref you can ref they can ref	I can be refing you can be refing she can be refing we can be refing you can be refing they can be refing
Perfect	V-ing perfect
I can have refed you can have refed she can have refed we can have refed you can have refed they can have refed	I can have been refing you can have been refing she can have been refing we can have been refing you can have been refing they can have been refing

Negation

Simple form	V-ing form
I cannot ref you cannot ref she cannot ref we cannot ref you cannot ref they cannot ref	I cannot be refing you cannot be refing she cannot be refing we cannot be refing you cannot be refing they cannot be refing
Perfect	V-ing perfect
I cannot have refed you cannot have refed she cannot have refed we cannot have refed you cannot have refed they cannot have refed	I cannot have been refing you cannot have been refing she cannot have been refing we cannot have been refing you cannot have been refing they cannot have been refing

Interrogative form

Simple form	V-ing form
can I ref? can you ref? can she ref? can we ref? can you ref? can they ref?	can I be refing? can you be refing? can she be refing? can we be refing? can you be refing? can they be refing?
Perfect	V-ing perfect
can I have refed? can you have refed? can she have refed? can we have refed? can you have refed? can they have refed?	can I have been refing? can you have been refing? can she have been refing? can we have been refing? can you have been refing? can they have been refing?

Interro-negative form

Simple form	V-ing form
can I not ref? can you not ref? can she not ref? can we not ref? can you not ref? can they not ref?	can I not be refing? can you not be refing? can she not be refing? can we not be refing? can you not be refing? can they not be refing?
Perfect	V-ing perfect
can I not have refed? can you not have refed? can she not have refed? can we not have refed? can you not have refed? can they not have refed?	can I not have been refing? can you not have been refing? can she not have been refing? can we not have been refing? can you not have been refing? can they not have been refing?