Warning, this verb may not exist. Conjugation is given as example.
Affirmation
Simple form
I could achieve achieve you could achieve achieve he could achieve achieve we could achieve achieve you could achieve achieve they could achieve achieve
V-ing form
I could be achieve achieving you could be achieve achieving he could be achieve achieving we could be achieve achieving you could be achieve achieving they could be achieve achieving
Perfect
I could have achieve achieved you could have achieve achieved he could have achieve achieved we could have achieve achieved you could have achieve achieved they could have achieve achieved
V-ing perfect
I could have been achieve achieving you could have been achieve achieving he could have been achieve achieving we could have been achieve achieving you could have been achieve achieving they could have been achieve achieving
Negation
Simple form
I couldn't achieve achieve you couldn't achieve achieve he couldn't achieve achieve we couldn't achieve achieve you couldn't achieve achieve they couldn't achieve achieve
V-ing form
I couldn't be achieve achieving you couldn't be achieve achieving he couldn't be achieve achieving we couldn't be achieve achieving you couldn't be achieve achieving they couldn't be achieve achieving
Perfect
I couldn't have achieve achieved you couldn't have achieve achieved he couldn't have achieve achieved we couldn't have achieve achieved you couldn't have achieve achieved they couldn't have achieve achieved
V-ing perfect
I couldn't have been achieve achieving you couldn't have been achieve achieving he couldn't have been achieve achieving we couldn't have been achieve achieving you couldn't have been achieve achieving they couldn't have been achieve achieving
Interrogative form
Simple form
could I achieve achieve? could you achieve achieve? could he achieve achieve? could we achieve achieve? could you achieve achieve? could they achieve achieve?
V-ing form
could I be achieve achieving? could you be achieve achieving? could he be achieve achieving? could we be achieve achieving? could you be achieve achieving? could they be achieve achieving?
Perfect
could I have achieve achieved? could you have achieve achieved? could he have achieve achieved? could we have achieve achieved? could you have achieve achieved? could they have achieve achieved?
V-ing perfect
could I have been achieve achieving? could you have been achieve achieving? could he have been achieve achieving? could we have been achieve achieving? could you have been achieve achieving? could they have been achieve achieving?
Interro-negative form
Simple form
couldn't I achieve achieve? couldn't you achieve achieve? couldn't he achieve achieve? couldn't we achieve achieve? couldn't you achieve achieve? couldn't they achieve achieve?
V-ing form
couldn't I be achieve achieving? couldn't you be achieve achieving? couldn't he be achieve achieving? couldn't we be achieve achieving? couldn't you be achieve achieving? couldn't they be achieve achieving?
Perfect
couldn't I have achieve achieved? couldn't you have achieve achieved? couldn't he have achieve achieved? couldn't we have achieve achieved? couldn't you have achieve achieved? couldn't they have achieve achieved?
V-ing perfect
couldn't I have been achieve achieving? couldn't you have been achieve achieving? couldn't he have been achieve achieving? couldn't we have been achieve achieving? couldn't you have been achieve achieving? couldn't they have been achieve achieving?