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