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