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