I could overacheive you could overacheive he could overacheive we could overacheive you could overacheive they could overacheive
V-ing form
I could be overacheiving you could be overacheiving he could be overacheiving we could be overacheiving you could be overacheiving they could be overacheiving
Perfect
I could have overacheived you could have overacheived he could have overacheived we could have overacheived you could have overacheived they could have overacheived
V-ing perfect
I could have been overacheiving you could have been overacheiving he could have been overacheiving we could have been overacheiving you could have been overacheiving they could have been overacheiving
Negation
Simple form
I could not overacheive you could not overacheive he could not overacheive we could not overacheive you could not overacheive they could not overacheive
V-ing form
I could not be overacheiving you could not be overacheiving he could not be overacheiving we could not be overacheiving you could not be overacheiving they could not be overacheiving
Perfect
I could not have overacheived you could not have overacheived he could not have overacheived we could not have overacheived you could not have overacheived they could not have overacheived
V-ing perfect
I could not have been overacheiving you could not have been overacheiving he could not have been overacheiving we could not have been overacheiving you could not have been overacheiving they could not have been overacheiving
Interrogative form
Simple form
could I overacheive? could you overacheive? could he overacheive? could we overacheive? could you overacheive? could they overacheive?
V-ing form
could I be overacheiving? could you be overacheiving? could he be overacheiving? could we be overacheiving? could you be overacheiving? could they be overacheiving?
Perfect
could I have overacheived? could you have overacheived? could he have overacheived? could we have overacheived? could you have overacheived? could they have overacheived?
V-ing perfect
could I have been overacheiving? could you have been overacheiving? could he have been overacheiving? could we have been overacheiving? could you have been overacheiving? could they have been overacheiving?
Interro-negative form
Simple form
could I not overacheive? could you not overacheive? could he not overacheive? could we not overacheive? could you not overacheive? could they not overacheive?
V-ing form
could I not be overacheiving? could you not be overacheiving? could he not be overacheiving? could we not be overacheiving? could you not be overacheiving? could they not be overacheiving?
Perfect
could I not have overacheived? could you not have overacheived? could he not have overacheived? could we not have overacheived? could you not have overacheived? could they not have overacheived?
V-ing perfect
could I not have been overacheiving? could you not have been overacheiving? could he not have been overacheiving? could we not have been overacheiving? could you not have been overacheiving? could they not have been overacheiving?