could detect
Regular verb: detect - detected- detected

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could detect
you could detect
she could detect
we could detect
you could detect
they could detect 	I could be detecting
you could be detecting
she could be detecting
we could be detecting
you could be detecting
they could be detecting	I could have detected
you could have detected
she could have detected
we could have detected
you could have detected
they could have detected	I could have been detecting
you could have been detecting
she could have been detecting
we could have been detecting
you could have been detecting
they could have been detecting	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't detect
you couldn't detect
she couldn't detect
we couldn't detect
you couldn't detect
they couldn't detect 	I couldn't be detecting
you couldn't be detecting
she couldn't be detecting
we couldn't be detecting
you couldn't be detecting
they couldn't be detecting	I couldn't have detected
you couldn't have detected
she couldn't have detected
we couldn't have detected
you couldn't have detected
they couldn't have detected	I couldn't have been detecting
you couldn't have been detecting
she couldn't have been detecting
we couldn't have been detecting
you couldn't have been detecting
they couldn't have been detecting	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I detect?
could you detect?
could she detect?
could we detect?
could you detect?
could they detect? 	could I be detecting?
could you be detecting?
could she be detecting?
could we be detecting?
could you be detecting?
could they be detecting? 	could I have detected?
could you have detected?
could she have detected?
could we have detected?
could you have detected?
could they have detected? 	could I have been detecting?
could you have been detecting?
could she have been detecting?
could we have been detecting?
could you have been detecting?
could they have been detecting? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I detect?
couldn't you detect?
couldn't she detect?
couldn't we detect?
couldn't you detect?
couldn't they detect? 	couldn't I be detecting?
couldn't you be detecting?
couldn't she be detecting?
couldn't we be detecting?
couldn't you be detecting?
couldn't they be detecting? 	couldn't I have detected?
couldn't you have detected?
couldn't she have detected?
couldn't we have detected?
couldn't you have detected?
couldn't they have detected? 	couldn't I have been detecting?
couldn't you have been detecting?
couldn't she have been detecting?
couldn't we have been detecting?
couldn't you have been detecting?
couldn't they have been detecting?