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