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