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