English verb conjugation
COULD TUBE

Regular verb: tube - tubed - tubed

Affirmation

Simple form	V-ing form
I could tube you could tube he could tube we could tube you could tube they could tube	I could be tubing you could be tubing he 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 he 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 he 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 couldn't tube you couldn't tube he couldn't tube we couldn't tube you couldn't tube they couldn't tube	I couldn't be tubing you couldn't be tubing he couldn't be tubing we couldn't be tubing you couldn't be tubing they couldn't be tubing
Perfect	V-ing perfect
I couldn't have tubed you couldn't have tubed he couldn't have tubed we couldn't have tubed you couldn't have tubed they couldn't have tubed	I couldn't have been tubing you couldn't have been tubing he couldn't have been tubing we couldn't have been tubing you couldn't have been tubing they couldn't have been tubing

Interrogative form

Simple form	V-ing form
could I tube? could you tube? could he tube? could we tube? could you tube? could they tube?	could I be tubing? could you be tubing? could he 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 he 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 he 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
couldn't I tube? couldn't you tube? couldn't he tube? couldn't we tube? couldn't you tube? couldn't they tube?	couldn't I be tubing? couldn't you be tubing? couldn't he be tubing? couldn't we be tubing? couldn't you be tubing? couldn't they be tubing?
Perfect	V-ing perfect
couldn't I have tubed? couldn't you have tubed? couldn't he have tubed? couldn't we have tubed? couldn't you have tubed? couldn't they have tubed?	couldn't I have been tubing? couldn't you have been tubing? couldn't he have been tubing? couldn't we have been tubing? couldn't you have been tubing? couldn't they have been tubing?