I could leister you could leister she could leister we could leister you could leister they could leister
V-ing form
I could be leistering you could be leistering she could be leistering we could be leistering you could be leistering they could be leistering
Perfect
I could have leistered you could have leistered she 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 she 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 she 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 she 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 she 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 she 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 she leister? could we leister? could you leister? could they leister?
V-ing form
could I be leistering? could you be leistering? could she be leistering? could we be leistering? could you be leistering? could they be leistering?
Perfect
could I have leistered? could you have leistered? could she 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 she 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 she 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 she 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 she 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 she have been leistering? couldn't we have been leistering? couldn't you have been leistering? couldn't they have been leistering?