I could detect you could detect he could detect we could detect you could detect they could detect
V-ing form
I could be detecting you could be detecting he could be detecting we could be detecting you could be detecting they could be detecting
Perfect
I could have detected you could have detected he could have detected we could have detected you could have detected they could have detected
V-ing perfect
I could have been detecting you could have been detecting he could have been detecting we could have been detecting you could have been detecting they could have been detecting
Negation
Simple form
I could not detect you could not detect he could not detect we could not detect you could not detect they could not detect
V-ing form
I could not be detecting you could not be detecting he could not be detecting we could not be detecting you could not be detecting they could not be detecting
Perfect
I could not have detected you could not have detected he could not have detected we could not have detected you could not have detected they could not have detected
V-ing perfect
I could not have been detecting you could not have been detecting he could not have been detecting we could not have been detecting you could not have been detecting they could not have been detecting
Interrogative form
Simple form
could I detect? could you detect? could he detect? could we detect? could you detect? could they detect?
V-ing form
could I be detecting? could you be detecting? could he be detecting? could we be detecting? could you be detecting? could they be detecting?
Perfect
could I have detected? could you have detected? could he have detected? could we have detected? could you have detected? could they have detected?
V-ing perfect
could I have been detecting? could you have been detecting? could he have been detecting? could we have been detecting? could you have been detecting? could they have been detecting?
Interro-negative form
Simple form
could I not detect? could you not detect? could he not detect? could we not detect? could you not detect? could they not detect?
V-ing form
could I not be detecting? could you not be detecting? could he not be detecting? could we not be detecting? could you not be detecting? could they not be detecting?
Perfect
could I not have detected? could you not have detected? could he not have detected? could we not have detected? could you not have detected? could they not have detected?
V-ing perfect
could I not have been detecting? could you not have been detecting? could he not have been detecting? could we not have been detecting? could you not have been detecting? could they not have been detecting?