I could achieve you could achieve she could achieve we could achieve you could achieve they could achieve
V-ing form
I could be achieving you could be achieving she could be achieving we could be achieving you could be achieving they could be achieving
Perfect
I could have achieved you could have achieved she could have achieved we could have achieved you could have achieved they could have achieved
V-ing perfect
I could have been achieving you could have been achieving she could have been achieving we could have been achieving you could have been achieving they could have been achieving
Negation
Simple form
I could not achieve you could not achieve she could not achieve we could not achieve you could not achieve they could not achieve
V-ing form
I could not be achieving you could not be achieving she could not be achieving we could not be achieving you could not be achieving they could not be achieving
Perfect
I could not have achieved you could not have achieved she could not have achieved we could not have achieved you could not have achieved they could not have achieved
V-ing perfect
I could not have been achieving you could not have been achieving she could not have been achieving we could not have been achieving you could not have been achieving they could not have been achieving
Interrogative form
Simple form
could I achieve? could you achieve? could she achieve? could we achieve? could you achieve? could they achieve?
V-ing form
could I be achieving? could you be achieving? could she be achieving? could we be achieving? could you be achieving? could they be achieving?
Perfect
could I have achieved? could you have achieved? could she have achieved? could we have achieved? could you have achieved? could they have achieved?
V-ing perfect
could I have been achieving? could you have been achieving? could she have been achieving? could we have been achieving? could you have been achieving? could they have been achieving?
Interro-negative form
Simple form
could I not achieve? could you not achieve? could she not achieve? could we not achieve? could you not achieve? could they not achieve?
V-ing form
could I not be achieving? could you not be achieving? could she not be achieving? could we not be achieving? could you not be achieving? could they not be achieving?
Perfect
could I not have achieved? could you not have achieved? could she not have achieved? could we not have achieved? could you not have achieved? could they not have achieved?
V-ing perfect
could I not have been achieving? could you not have been achieving? could she not have been achieving? could we not have been achieving? could you not have been achieving? could they not have been achieving?