English verb conjugation
COULD SPIFF

Regular verb: spiff - spiffed - spiffed

Affirmation

Simple form	V-ing form
I could spiff you could spiff he could spiff we could spiff you could spiff they could spiff	I could be spiffing you could be spiffing he could be spiffing we could be spiffing you could be spiffing they could be spiffing
Perfect	V-ing perfect
I could have spiffed you could have spiffed he could have spiffed we could have spiffed you could have spiffed they could have spiffed	I could have been spiffing you could have been spiffing he could have been spiffing we could have been spiffing you could have been spiffing they could have been spiffing

Negation

Simple form	V-ing form
I could not spiff you could not spiff he could not spiff we could not spiff you could not spiff they could not spiff	I could not be spiffing you could not be spiffing he could not be spiffing we could not be spiffing you could not be spiffing they could not be spiffing
Perfect	V-ing perfect
I could not have spiffed you could not have spiffed he could not have spiffed we could not have spiffed you could not have spiffed they could not have spiffed	I could not have been spiffing you could not have been spiffing he could not have been spiffing we could not have been spiffing you could not have been spiffing they could not have been spiffing

Interrogative form

Simple form	V-ing form
could I spiff? could you spiff? could he spiff? could we spiff? could you spiff? could they spiff?	could I be spiffing? could you be spiffing? could he be spiffing? could we be spiffing? could you be spiffing? could they be spiffing?
Perfect	V-ing perfect
could I have spiffed? could you have spiffed? could he have spiffed? could we have spiffed? could you have spiffed? could they have spiffed?	could I have been spiffing? could you have been spiffing? could he have been spiffing? could we have been spiffing? could you have been spiffing? could they have been spiffing?

Interro-negative form

Simple form	V-ing form
could I not spiff? could you not spiff? could he not spiff? could we not spiff? could you not spiff? could they not spiff?	could I not be spiffing? could you not be spiffing? could he not be spiffing? could we not be spiffing? could you not be spiffing? could they not be spiffing?
Perfect	V-ing perfect
could I not have spiffed? could you not have spiffed? could he not have spiffed? could we not have spiffed? could you not have spiffed? could they not have spiffed?	could I not have been spiffing? could you not have been spiffing? could he not have been spiffing? could we not have been spiffing? could you not have been spiffing? could they not have been spiffing?