Warning, this verb may not exist. Conjugation is given as example.
Affirmation
Simple form
I could uderstate sth you could uderstate sth he could uderstate sth we could uderstate sth you could uderstate sth they could uderstate sth
V-ing form
I could be uderstate sthing you could be uderstate sthing he could be uderstate sthing we could be uderstate sthing you could be uderstate sthing they could be uderstate sthing
Perfect
I could have uderstate sthed you could have uderstate sthed he could have uderstate sthed we could have uderstate sthed you could have uderstate sthed they could have uderstate sthed
V-ing perfect
I could have been uderstate sthing you could have been uderstate sthing he could have been uderstate sthing we could have been uderstate sthing you could have been uderstate sthing they could have been uderstate sthing
Negation
Simple form
I couldn't uderstate sth you couldn't uderstate sth he couldn't uderstate sth we couldn't uderstate sth you couldn't uderstate sth they couldn't uderstate sth
V-ing form
I couldn't be uderstate sthing you couldn't be uderstate sthing he couldn't be uderstate sthing we couldn't be uderstate sthing you couldn't be uderstate sthing they couldn't be uderstate sthing
Perfect
I couldn't have uderstate sthed you couldn't have uderstate sthed he couldn't have uderstate sthed we couldn't have uderstate sthed you couldn't have uderstate sthed they couldn't have uderstate sthed
V-ing perfect
I couldn't have been uderstate sthing you couldn't have been uderstate sthing he couldn't have been uderstate sthing we couldn't have been uderstate sthing you couldn't have been uderstate sthing they couldn't have been uderstate sthing
Interrogative form
Simple form
could I uderstate sth? could you uderstate sth? could he uderstate sth? could we uderstate sth? could you uderstate sth? could they uderstate sth?
V-ing form
could I be uderstate sthing? could you be uderstate sthing? could he be uderstate sthing? could we be uderstate sthing? could you be uderstate sthing? could they be uderstate sthing?
Perfect
could I have uderstate sthed? could you have uderstate sthed? could he have uderstate sthed? could we have uderstate sthed? could you have uderstate sthed? could they have uderstate sthed?
V-ing perfect
could I have been uderstate sthing? could you have been uderstate sthing? could he have been uderstate sthing? could we have been uderstate sthing? could you have been uderstate sthing? could they have been uderstate sthing?
Interro-negative form
Simple form
couldn't I uderstate sth? couldn't you uderstate sth? couldn't he uderstate sth? couldn't we uderstate sth? couldn't you uderstate sth? couldn't they uderstate sth?
V-ing form
couldn't I be uderstate sthing? couldn't you be uderstate sthing? couldn't he be uderstate sthing? couldn't we be uderstate sthing? couldn't you be uderstate sthing? couldn't they be uderstate sthing?
Perfect
couldn't I have uderstate sthed? couldn't you have uderstate sthed? couldn't he have uderstate sthed? couldn't we have uderstate sthed? couldn't you have uderstate sthed? couldn't they have uderstate sthed?
V-ing perfect
couldn't I have been uderstate sthing? couldn't you have been uderstate sthing? couldn't he have been uderstate sthing? couldn't we have been uderstate sthing? couldn't you have been uderstate sthing? couldn't they have been uderstate sthing?