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