I could rivet you could rivet he could rivet we could rivet you could rivet they could rivet
V-ing form
I could be riveting you could be riveting he could be riveting we could be riveting you could be riveting they could be riveting
Perfect
I could have riveted you could have riveted he could have riveted we could have riveted you could have riveted they could have riveted
V-ing perfect
I could have been riveting you could have been riveting he could have been riveting we could have been riveting you could have been riveting they could have been riveting
Negation
Simple form
I could not rivet you could not rivet he could not rivet we could not rivet you could not rivet they could not rivet
V-ing form
I could not be riveting you could not be riveting he could not be riveting we could not be riveting you could not be riveting they could not be riveting
Perfect
I could not have riveted you could not have riveted he could not have riveted we could not have riveted you could not have riveted they could not have riveted
V-ing perfect
I could not have been riveting you could not have been riveting he could not have been riveting we could not have been riveting you could not have been riveting they could not have been riveting
Interrogative form
Simple form
could I rivet? could you rivet? could he rivet? could we rivet? could you rivet? could they rivet?
V-ing form
could I be riveting? could you be riveting? could he be riveting? could we be riveting? could you be riveting? could they be riveting?
Perfect
could I have riveted? could you have riveted? could he have riveted? could we have riveted? could you have riveted? could they have riveted?
V-ing perfect
could I have been riveting? could you have been riveting? could he have been riveting? could we have been riveting? could you have been riveting? could they have been riveting?
Interro-negative form
Simple form
could I not rivet? could you not rivet? could he not rivet? could we not rivet? could you not rivet? could they not rivet?
V-ing form
could I not be riveting? could you not be riveting? could he not be riveting? could we not be riveting? could you not be riveting? could they not be riveting?
Perfect
could I not have riveted? could you not have riveted? could he not have riveted? could we not have riveted? could you not have riveted? could they not have riveted?
V-ing perfect
could I not have been riveting? could you not have been riveting? could he not have been riveting? could we not have been riveting? could you not have been riveting? could they not have been riveting?