I could append you could append she could append we could append you could append they could append
V-ing form
I could be appending you could be appending she could be appending we could be appending you could be appending they could be appending
Perfect
I could have appended you could have appended she could have appended we could have appended you could have appended they could have appended
V-ing perfect
I could have been appending you could have been appending she could have been appending we could have been appending you could have been appending they could have been appending
Negation
Simple form
I could not append you could not append she could not append we could not append you could not append they could not append
V-ing form
I could not be appending you could not be appending she could not be appending we could not be appending you could not be appending they could not be appending
Perfect
I could not have appended you could not have appended she could not have appended we could not have appended you could not have appended they could not have appended
V-ing perfect
I could not have been appending you could not have been appending she could not have been appending we could not have been appending you could not have been appending they could not have been appending
Interrogative form
Simple form
could I append? could you append? could she append? could we append? could you append? could they append?
V-ing form
could I be appending? could you be appending? could she be appending? could we be appending? could you be appending? could they be appending?
Perfect
could I have appended? could you have appended? could she have appended? could we have appended? could you have appended? could they have appended?
V-ing perfect
could I have been appending? could you have been appending? could she have been appending? could we have been appending? could you have been appending? could they have been appending?
Interro-negative form
Simple form
could I not append? could you not append? could she not append? could we not append? could you not append? could they not append?
V-ing form
could I not be appending? could you not be appending? could she not be appending? could we not be appending? could you not be appending? could they not be appending?
Perfect
could I not have appended? could you not have appended? could she not have appended? could we not have appended? could you not have appended? could they not have appended?
V-ing perfect
could I not have been appending? could you not have been appending? could she not have been appending? could we not have been appending? could you not have been appending? could they not have been appending?