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