English verb conjugation
COULD DRUB

Regular verb: drub - drubbed - drubbed

Affirmation

Simple form	V-ing form
I could drub you could drub he could drub we could drub you could drub they could drub	I could be drubbing you could be drubbing he could be drubbing we could be drubbing you could be drubbing they could be drubbing
Perfect	V-ing perfect
I could have drubbed you could have drubbed he could have drubbed we could have drubbed you could have drubbed they could have drubbed	I could have been drubbing you could have been drubbing he could have been drubbing we could have been drubbing you could have been drubbing they could have been drubbing

Negation

Simple form	V-ing form
I could not drub you could not drub he could not drub we could not drub you could not drub they could not drub	I could not be drubbing you could not be drubbing he could not be drubbing we could not be drubbing you could not be drubbing they could not be drubbing
Perfect	V-ing perfect
I could not have drubbed you could not have drubbed he could not have drubbed we could not have drubbed you could not have drubbed they could not have drubbed	I could not have been drubbing you could not have been drubbing he could not have been drubbing we could not have been drubbing you could not have been drubbing they could not have been drubbing

Interrogative form

Simple form	V-ing form
could I drub? could you drub? could he drub? could we drub? could you drub? could they drub?	could I be drubbing? could you be drubbing? could he be drubbing? could we be drubbing? could you be drubbing? could they be drubbing?
Perfect	V-ing perfect
could I have drubbed? could you have drubbed? could he have drubbed? could we have drubbed? could you have drubbed? could they have drubbed?	could I have been drubbing? could you have been drubbing? could he have been drubbing? could we have been drubbing? could you have been drubbing? could they have been drubbing?

Interro-negative form

Simple form	V-ing form
could I not drub? could you not drub? could he not drub? could we not drub? could you not drub? could they not drub?	could I not be drubbing? could you not be drubbing? could he not be drubbing? could we not be drubbing? could you not be drubbing? could they not be drubbing?
Perfect	V-ing perfect
could I not have drubbed? could you not have drubbed? could he not have drubbed? could we not have drubbed? could you not have drubbed? could they not have drubbed?	could I not have been drubbing? could you not have been drubbing? could he not have been drubbing? could we not have been drubbing? could you not have been drubbing? could they not have been drubbing?