I could quintuple you could quintuple he could quintuple we could quintuple you could quintuple they could quintuple
V-ing form
I could be quintupling you could be quintupling he could be quintupling we could be quintupling you could be quintupling they could be quintupling
Perfect
I could have quintupled you could have quintupled he could have quintupled we could have quintupled you could have quintupled they could have quintupled
V-ing perfect
I could have been quintupling you could have been quintupling he could have been quintupling we could have been quintupling you could have been quintupling they could have been quintupling
Negation
Simple form
I could not quintuple you could not quintuple he could not quintuple we could not quintuple you could not quintuple they could not quintuple
V-ing form
I could not be quintupling you could not be quintupling he could not be quintupling we could not be quintupling you could not be quintupling they could not be quintupling
Perfect
I could not have quintupled you could not have quintupled he could not have quintupled we could not have quintupled you could not have quintupled they could not have quintupled
V-ing perfect
I could not have been quintupling you could not have been quintupling he could not have been quintupling we could not have been quintupling you could not have been quintupling they could not have been quintupling
Interrogative form
Simple form
could I quintuple? could you quintuple? could he quintuple? could we quintuple? could you quintuple? could they quintuple?
V-ing form
could I be quintupling? could you be quintupling? could he be quintupling? could we be quintupling? could you be quintupling? could they be quintupling?
Perfect
could I have quintupled? could you have quintupled? could he have quintupled? could we have quintupled? could you have quintupled? could they have quintupled?
V-ing perfect
could I have been quintupling? could you have been quintupling? could he have been quintupling? could we have been quintupling? could you have been quintupling? could they have been quintupling?
Interro-negative form
Simple form
could I not quintuple? could you not quintuple? could he not quintuple? could we not quintuple? could you not quintuple? could they not quintuple?
V-ing form
could I not be quintupling? could you not be quintupling? could he not be quintupling? could we not be quintupling? could you not be quintupling? could they not be quintupling?
Perfect
could I not have quintupled? could you not have quintupled? could he not have quintupled? could we not have quintupled? could you not have quintupled? could they not have quintupled?
V-ing perfect
could I not have been quintupling? could you not have been quintupling? could he not have been quintupling? could we not have been quintupling? could you not have been quintupling? could they not have been quintupling?