I could greet you could greet she could greet we could greet you could greet they could greet
V-ing form
I could be greeting you could be greeting she could be greeting we could be greeting you could be greeting they could be greeting
Perfect
I could have greeted you could have greeted she could have greeted we could have greeted you could have greeted they could have greeted
V-ing perfect
I could have been greeting you could have been greeting she could have been greeting we could have been greeting you could have been greeting they could have been greeting
Negation
Simple form
I couldn't greet you couldn't greet she couldn't greet we couldn't greet you couldn't greet they couldn't greet
V-ing form
I couldn't be greeting you couldn't be greeting she couldn't be greeting we couldn't be greeting you couldn't be greeting they couldn't be greeting
Perfect
I couldn't have greeted you couldn't have greeted she couldn't have greeted we couldn't have greeted you couldn't have greeted they couldn't have greeted
V-ing perfect
I couldn't have been greeting you couldn't have been greeting she couldn't have been greeting we couldn't have been greeting you couldn't have been greeting they couldn't have been greeting
Interrogative form
Simple form
could I greet? could you greet? could she greet? could we greet? could you greet? could they greet?
V-ing form
could I be greeting? could you be greeting? could she be greeting? could we be greeting? could you be greeting? could they be greeting?
Perfect
could I have greeted? could you have greeted? could she have greeted? could we have greeted? could you have greeted? could they have greeted?
V-ing perfect
could I have been greeting? could you have been greeting? could she have been greeting? could we have been greeting? could you have been greeting? could they have been greeting?
Interro-negative form
Simple form
couldn't I greet? couldn't you greet? couldn't she greet? couldn't we greet? couldn't you greet? couldn't they greet?
V-ing form
couldn't I be greeting? couldn't you be greeting? couldn't she be greeting? couldn't we be greeting? couldn't you be greeting? couldn't they be greeting?
Perfect
couldn't I have greeted? couldn't you have greeted? couldn't she have greeted? couldn't we have greeted? couldn't you have greeted? couldn't they have greeted?
V-ing perfect
couldn't I have been greeting? couldn't you have been greeting? couldn't she have been greeting? couldn't we have been greeting? couldn't you have been greeting? couldn't they have been greeting?