English verb conjugation
COULD STUB

Regular verb: stub - stubbed - stubbed

Affirmation

Simple form	V-ing form
I could stub you could stub he could stub we could stub you could stub they could stub	I could be stubbing you could be stubbing he could be stubbing we could be stubbing you could be stubbing they could be stubbing
Perfect	V-ing perfect
I could have stubbed you could have stubbed he could have stubbed we could have stubbed you could have stubbed they could have stubbed	I could have been stubbing you could have been stubbing he could have been stubbing we could have been stubbing you could have been stubbing they could have been stubbing

Negation

Simple form	V-ing form
I couldn't stub you couldn't stub he couldn't stub we couldn't stub you couldn't stub they couldn't stub	I couldn't be stubbing you couldn't be stubbing he couldn't be stubbing we couldn't be stubbing you couldn't be stubbing they couldn't be stubbing
Perfect	V-ing perfect
I couldn't have stubbed you couldn't have stubbed he couldn't have stubbed we couldn't have stubbed you couldn't have stubbed they couldn't have stubbed	I couldn't have been stubbing you couldn't have been stubbing he couldn't have been stubbing we couldn't have been stubbing you couldn't have been stubbing they couldn't have been stubbing

Interrogative form

Simple form	V-ing form
could I stub? could you stub? could he stub? could we stub? could you stub? could they stub?	could I be stubbing? could you be stubbing? could he be stubbing? could we be stubbing? could you be stubbing? could they be stubbing?
Perfect	V-ing perfect
could I have stubbed? could you have stubbed? could he have stubbed? could we have stubbed? could you have stubbed? could they have stubbed?	could I have been stubbing? could you have been stubbing? could he have been stubbing? could we have been stubbing? could you have been stubbing? could they have been stubbing?

Interro-negative form

Simple form	V-ing form
couldn't I stub? couldn't you stub? couldn't he stub? couldn't we stub? couldn't you stub? couldn't they stub?	couldn't I be stubbing? couldn't you be stubbing? couldn't he be stubbing? couldn't we be stubbing? couldn't you be stubbing? couldn't they be stubbing?
Perfect	V-ing perfect
couldn't I have stubbed? couldn't you have stubbed? couldn't he have stubbed? couldn't we have stubbed? couldn't you have stubbed? couldn't they have stubbed?	couldn't I have been stubbing? couldn't you have been stubbing? couldn't he have been stubbing? couldn't we have been stubbing? couldn't you have been stubbing? couldn't they have been stubbing?