I could oil you could oil he could oil we could oil you could oil they could oil
V-ing form
I could be oiling you could be oiling he could be oiling we could be oiling you could be oiling they could be oiling
Perfect
I could have oiled you could have oiled he could have oiled we could have oiled you could have oiled they could have oiled
V-ing perfect
I could have been oiling you could have been oiling he could have been oiling we could have been oiling you could have been oiling they could have been oiling
Negation
Simple form
I could not oil you could not oil he could not oil we could not oil you could not oil they could not oil
V-ing form
I could not be oiling you could not be oiling he could not be oiling we could not be oiling you could not be oiling they could not be oiling
Perfect
I could not have oiled you could not have oiled he could not have oiled we could not have oiled you could not have oiled they could not have oiled
V-ing perfect
I could not have been oiling you could not have been oiling he could not have been oiling we could not have been oiling you could not have been oiling they could not have been oiling
Interrogative form
Simple form
could I oil? could you oil? could he oil? could we oil? could you oil? could they oil?
V-ing form
could I be oiling? could you be oiling? could he be oiling? could we be oiling? could you be oiling? could they be oiling?
Perfect
could I have oiled? could you have oiled? could he have oiled? could we have oiled? could you have oiled? could they have oiled?
V-ing perfect
could I have been oiling? could you have been oiling? could he have been oiling? could we have been oiling? could you have been oiling? could they have been oiling?
Interro-negative form
Simple form
could I not oil? could you not oil? could he not oil? could we not oil? could you not oil? could they not oil?
V-ing form
could I not be oiling? could you not be oiling? could he not be oiling? could we not be oiling? could you not be oiling? could they not be oiling?
Perfect
could I not have oiled? could you not have oiled? could he not have oiled? could we not have oiled? could you not have oiled? could they not have oiled?
V-ing perfect
could I not have been oiling? could you not have been oiling? could he not have been oiling? could we not have been oiling? could you not have been oiling? could they not have been oiling?