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