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