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