I could crumple you could crumple he could crumple we could crumple you could crumple they could crumple
V-ing form
I could be crumpling you could be crumpling he could be crumpling we could be crumpling you could be crumpling they could be crumpling
Perfect
I could have crumpled you could have crumpled he could have crumpled we could have crumpled you could have crumpled they could have crumpled
V-ing perfect
I could have been crumpling you could have been crumpling he could have been crumpling we could have been crumpling you could have been crumpling they could have been crumpling
Negation
Simple form
I couldn't crumple you couldn't crumple he couldn't crumple we couldn't crumple you couldn't crumple they couldn't crumple
V-ing form
I couldn't be crumpling you couldn't be crumpling he couldn't be crumpling we couldn't be crumpling you couldn't be crumpling they couldn't be crumpling
Perfect
I couldn't have crumpled you couldn't have crumpled he couldn't have crumpled we couldn't have crumpled you couldn't have crumpled they couldn't have crumpled
V-ing perfect
I couldn't have been crumpling you couldn't have been crumpling he couldn't have been crumpling we couldn't have been crumpling you couldn't have been crumpling they couldn't have been crumpling
Interrogative form
Simple form
could I crumple? could you crumple? could he crumple? could we crumple? could you crumple? could they crumple?
V-ing form
could I be crumpling? could you be crumpling? could he be crumpling? could we be crumpling? could you be crumpling? could they be crumpling?
Perfect
could I have crumpled? could you have crumpled? could he have crumpled? could we have crumpled? could you have crumpled? could they have crumpled?
V-ing perfect
could I have been crumpling? could you have been crumpling? could he have been crumpling? could we have been crumpling? could you have been crumpling? could they have been crumpling?
Interro-negative form
Simple form
couldn't I crumple? couldn't you crumple? couldn't he crumple? couldn't we crumple? couldn't you crumple? couldn't they crumple?
V-ing form
couldn't I be crumpling? couldn't you be crumpling? couldn't he be crumpling? couldn't we be crumpling? couldn't you be crumpling? couldn't they be crumpling?
Perfect
couldn't I have crumpled? couldn't you have crumpled? couldn't he have crumpled? couldn't we have crumpled? couldn't you have crumpled? couldn't they have crumpled?
V-ing perfect
couldn't I have been crumpling? couldn't you have been crumpling? couldn't he have been crumpling? couldn't we have been crumpling? couldn't you have been crumpling? couldn't they have been crumpling?