English verb conjugation
COULD REFEREE

Regular verb: referee - refereed - refereed

Affirmation

Simple form	V-ing form
I could referee you could referee he could referee we could referee you could referee they could referee	I could be refereeing you could be refereeing he could be refereeing we could be refereeing you could be refereeing they could be refereeing
Perfect	V-ing perfect
I could have refereed you could have refereed he could have refereed we could have refereed you could have refereed they could have refereed	I could have been refereeing you could have been refereeing he could have been refereeing we could have been refereeing you could have been refereeing they could have been refereeing

Negation

Simple form	V-ing form
I couldn't referee you couldn't referee he couldn't referee we couldn't referee you couldn't referee they couldn't referee	I couldn't be refereeing you couldn't be refereeing he couldn't be refereeing we couldn't be refereeing you couldn't be refereeing they couldn't be refereeing
Perfect	V-ing perfect
I couldn't have refereed you couldn't have refereed he couldn't have refereed we couldn't have refereed you couldn't have refereed they couldn't have refereed	I couldn't have been refereeing you couldn't have been refereeing he couldn't have been refereeing we couldn't have been refereeing you couldn't have been refereeing they couldn't have been refereeing

Interrogative form

Simple form	V-ing form
could I referee? could you referee? could he referee? could we referee? could you referee? could they referee?	could I be refereeing? could you be refereeing? could he be refereeing? could we be refereeing? could you be refereeing? could they be refereeing?
Perfect	V-ing perfect
could I have refereed? could you have refereed? could he have refereed? could we have refereed? could you have refereed? could they have refereed?	could I have been refereeing? could you have been refereeing? could he have been refereeing? could we have been refereeing? could you have been refereeing? could they have been refereeing?

Interro-negative form

Simple form	V-ing form
couldn't I referee? couldn't you referee? couldn't he referee? couldn't we referee? couldn't you referee? couldn't they referee?	couldn't I be refereeing? couldn't you be refereeing? couldn't he be refereeing? couldn't we be refereeing? couldn't you be refereeing? couldn't they be refereeing?
Perfect	V-ing perfect
couldn't I have refereed? couldn't you have refereed? couldn't he have refereed? couldn't we have refereed? couldn't you have refereed? couldn't they have refereed?	couldn't I have been refereeing? couldn't you have been refereeing? couldn't he have been refereeing? couldn't we have been refereeing? couldn't you have been refereeing? couldn't they have been refereeing?