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 couldn't overacheive you couldn't overacheive he couldn't overacheive we couldn't overacheive you couldn't overacheive they couldn't overacheive
V-ing form
I couldn't be overacheiving you couldn't be overacheiving he couldn't be overacheiving we couldn't be overacheiving you couldn't be overacheiving they couldn't be overacheiving
Perfect
I couldn't have overacheived you couldn't have overacheived he couldn't have overacheived we couldn't have overacheived you couldn't have overacheived they couldn't have overacheived
V-ing perfect
I couldn't have been overacheiving you couldn't have been overacheiving he couldn't have been overacheiving we couldn't have been overacheiving you couldn't have been overacheiving they couldn't 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
couldn't I overacheive? couldn't you overacheive? couldn't he overacheive? couldn't we overacheive? couldn't you overacheive? couldn't they overacheive?
V-ing form
couldn't I be overacheiving? couldn't you be overacheiving? couldn't he be overacheiving? couldn't we be overacheiving? couldn't you be overacheiving? couldn't they be overacheiving?
Perfect
couldn't I have overacheived? couldn't you have overacheived? couldn't he have overacheived? couldn't we have overacheived? couldn't you have overacheived? couldn't they have overacheived?
V-ing perfect
couldn't I have been overacheiving? couldn't you have been overacheiving? couldn't he have been overacheiving? couldn't we have been overacheiving? couldn't you have been overacheiving? couldn't they have been overacheiving?