I could while you could while he could while we could while you could while they could while
V-ing form
I could be whiling you could be whiling he could be whiling we could be whiling you could be whiling they could be whiling
Perfect
I could have whiled you could have whiled he could have whiled we could have whiled you could have whiled they could have whiled
V-ing perfect
I could have been whiling you could have been whiling he could have been whiling we could have been whiling you could have been whiling they could have been whiling
Negation
Simple form
I could not while you could not while he could not while we could not while you could not while they could not while
V-ing form
I could not be whiling you could not be whiling he could not be whiling we could not be whiling you could not be whiling they could not be whiling
Perfect
I could not have whiled you could not have whiled he could not have whiled we could not have whiled you could not have whiled they could not have whiled
V-ing perfect
I could not have been whiling you could not have been whiling he could not have been whiling we could not have been whiling you could not have been whiling they could not have been whiling
Interrogative form
Simple form
could I while? could you while? could he while? could we while? could you while? could they while?
V-ing form
could I be whiling? could you be whiling? could he be whiling? could we be whiling? could you be whiling? could they be whiling?
Perfect
could I have whiled? could you have whiled? could he have whiled? could we have whiled? could you have whiled? could they have whiled?
V-ing perfect
could I have been whiling? could you have been whiling? could he have been whiling? could we have been whiling? could you have been whiling? could they have been whiling?
Interro-negative form
Simple form
could I not while? could you not while? could he not while? could we not while? could you not while? could they not while?
V-ing form
could I not be whiling? could you not be whiling? could he not be whiling? could we not be whiling? could you not be whiling? could they not be whiling?
Perfect
could I not have whiled? could you not have whiled? could he not have whiled? could we not have whiled? could you not have whiled? could they not have whiled?
V-ing perfect
could I not have been whiling? could you not have been whiling? could he not have been whiling? could we not have been whiling? could you not have been whiling? could they not have been whiling?