I could breakfast you could breakfast he could breakfast we could breakfast you could breakfast they could breakfast
V-ing form
I could be breakfasting you could be breakfasting he could be breakfasting we could be breakfasting you could be breakfasting they could be breakfasting
Perfect
I could have breakfasted you could have breakfasted he could have breakfasted we could have breakfasted you could have breakfasted they could have breakfasted
V-ing perfect
I could have been breakfasting you could have been breakfasting he could have been breakfasting we could have been breakfasting you could have been breakfasting they could have been breakfasting
Negation
Simple form
I could not breakfast you could not breakfast he could not breakfast we could not breakfast you could not breakfast they could not breakfast
V-ing form
I could not be breakfasting you could not be breakfasting he could not be breakfasting we could not be breakfasting you could not be breakfasting they could not be breakfasting
Perfect
I could not have breakfasted you could not have breakfasted he could not have breakfasted we could not have breakfasted you could not have breakfasted they could not have breakfasted
V-ing perfect
I could not have been breakfasting you could not have been breakfasting he could not have been breakfasting we could not have been breakfasting you could not have been breakfasting they could not have been breakfasting
Interrogative form
Simple form
could I breakfast? could you breakfast? could he breakfast? could we breakfast? could you breakfast? could they breakfast?
V-ing form
could I be breakfasting? could you be breakfasting? could he be breakfasting? could we be breakfasting? could you be breakfasting? could they be breakfasting?
Perfect
could I have breakfasted? could you have breakfasted? could he have breakfasted? could we have breakfasted? could you have breakfasted? could they have breakfasted?
V-ing perfect
could I have been breakfasting? could you have been breakfasting? could he have been breakfasting? could we have been breakfasting? could you have been breakfasting? could they have been breakfasting?
Interro-negative form
Simple form
could I not breakfast? could you not breakfast? could he not breakfast? could we not breakfast? could you not breakfast? could they not breakfast?
V-ing form
could I not be breakfasting? could you not be breakfasting? could he not be breakfasting? could we not be breakfasting? could you not be breakfasting? could they not be breakfasting?
Perfect
could I not have breakfasted? could you not have breakfasted? could he not have breakfasted? could we not have breakfasted? could you not have breakfasted? could they not have breakfasted?
V-ing perfect
could I not have been breakfasting? could you not have been breakfasting? could he not have been breakfasting? could we not have been breakfasting? could you not have been breakfasting? could they not have been breakfasting?