I could search you could search he could search we could search you could search they could search
V-ing form
I could be searching you could be searching he could be searching we could be searching you could be searching they could be searching
Perfect
I could have searched you could have searched he could have searched we could have searched you could have searched they could have searched
V-ing perfect
I could have been searching you could have been searching he could have been searching we could have been searching you could have been searching they could have been searching
Negation
Simple form
I could not search you could not search he could not search we could not search you could not search they could not search
V-ing form
I could not be searching you could not be searching he could not be searching we could not be searching you could not be searching they could not be searching
Perfect
I could not have searched you could not have searched he could not have searched we could not have searched you could not have searched they could not have searched
V-ing perfect
I could not have been searching you could not have been searching he could not have been searching we could not have been searching you could not have been searching they could not have been searching
Interrogative form
Simple form
could I search? could you search? could he search? could we search? could you search? could they search?
V-ing form
could I be searching? could you be searching? could he be searching? could we be searching? could you be searching? could they be searching?
Perfect
could I have searched? could you have searched? could he have searched? could we have searched? could you have searched? could they have searched?
V-ing perfect
could I have been searching? could you have been searching? could he have been searching? could we have been searching? could you have been searching? could they have been searching?
Interro-negative form
Simple form
could I not search? could you not search? could he not search? could we not search? could you not search? could they not search?
V-ing form
could I not be searching? could you not be searching? could he not be searching? could we not be searching? could you not be searching? could they not be searching?
Perfect
could I not have searched? could you not have searched? could he not have searched? could we not have searched? could you not have searched? could they not have searched?
V-ing perfect
could I not have been searching? could you not have been searching? could he not have been searching? could we not have been searching? could you not have been searching? could they not have been searching?