English verb conjugation
COULD TUBE

Regular verb: tube - tubed - tubed

Affirmation

Simple form	V-ing form
I could tube you could tube she could tube we could tube you could tube they could tube	I could be tubing you could be tubing she could be tubing we could be tubing you could be tubing they could be tubing
Perfect	V-ing perfect
I could have tubed you could have tubed she could have tubed we could have tubed you could have tubed they could have tubed	I could have been tubing you could have been tubing she could have been tubing we could have been tubing you could have been tubing they could have been tubing

Negation

Simple form	V-ing form
I could not tube you could not tube she could not tube we could not tube you could not tube they could not tube	I could not be tubing you could not be tubing she could not be tubing we could not be tubing you could not be tubing they could not be tubing
Perfect	V-ing perfect
I could not have tubed you could not have tubed she could not have tubed we could not have tubed you could not have tubed they could not have tubed	I could not have been tubing you could not have been tubing she could not have been tubing we could not have been tubing you could not have been tubing they could not have been tubing

Interrogative form

Simple form	V-ing form
could I tube? could you tube? could she tube? could we tube? could you tube? could they tube?	could I be tubing? could you be tubing? could she be tubing? could we be tubing? could you be tubing? could they be tubing?
Perfect	V-ing perfect
could I have tubed? could you have tubed? could she have tubed? could we have tubed? could you have tubed? could they have tubed?	could I have been tubing? could you have been tubing? could she have been tubing? could we have been tubing? could you have been tubing? could they have been tubing?

Interro-negative form

Simple form	V-ing form
could I not tube? could you not tube? could she not tube? could we not tube? could you not tube? could they not tube?	could I not be tubing? could you not be tubing? could she not be tubing? could we not be tubing? could you not be tubing? could they not be tubing?
Perfect	V-ing perfect
could I not have tubed? could you not have tubed? could she not have tubed? could we not have tubed? could you not have tubed? could they not have tubed?	could I not have been tubing? could you not have been tubing? could she not have been tubing? could we not have been tubing? could you not have been tubing? could they not have been tubing?