I could steam you could steam he could steam we could steam you could steam they could steam
V-ing form
I could be steaming you could be steaming he could be steaming we could be steaming you could be steaming they could be steaming
Perfect
I could have steamed you could have steamed he could have steamed we could have steamed you could have steamed they could have steamed
V-ing perfect
I could have been steaming you could have been steaming he could have been steaming we could have been steaming you could have been steaming they could have been steaming
Negation
Simple form
I could not steam you could not steam he could not steam we could not steam you could not steam they could not steam
V-ing form
I could not be steaming you could not be steaming he could not be steaming we could not be steaming you could not be steaming they could not be steaming
Perfect
I could not have steamed you could not have steamed he could not have steamed we could not have steamed you could not have steamed they could not have steamed
V-ing perfect
I could not have been steaming you could not have been steaming he could not have been steaming we could not have been steaming you could not have been steaming they could not have been steaming
Interrogative form
Simple form
could I steam? could you steam? could he steam? could we steam? could you steam? could they steam?
V-ing form
could I be steaming? could you be steaming? could he be steaming? could we be steaming? could you be steaming? could they be steaming?
Perfect
could I have steamed? could you have steamed? could he have steamed? could we have steamed? could you have steamed? could they have steamed?
V-ing perfect
could I have been steaming? could you have been steaming? could he have been steaming? could we have been steaming? could you have been steaming? could they have been steaming?
Interro-negative form
Simple form
could I not steam? could you not steam? could he not steam? could we not steam? could you not steam? could they not steam?
V-ing form
could I not be steaming? could you not be steaming? could he not be steaming? could we not be steaming? could you not be steaming? could they not be steaming?
Perfect
could I not have steamed? could you not have steamed? could he not have steamed? could we not have steamed? could you not have steamed? could they not have steamed?
V-ing perfect
could I not have been steaming? could you not have been steaming? could he not have been steaming? could we not have been steaming? could you not have been steaming? could they not have been steaming?