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 couldn't tube you couldn't tube she 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 she 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 she 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 she 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 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
couldn't I tube? couldn't you tube? couldn't she 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 she 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 she 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 she have been tubing? couldn't we have been tubing? couldn't you have been tubing? couldn't they have been tubing?