English verb conjugation
COULD PERFORM

Regular verb: perform - performed - performed

Affirmation

Simple form	V-ing form
I could perform you could perform he could perform we could perform you could perform they could perform	I could be performing you could be performing he could be performing we could be performing you could be performing they could be performing
Perfect	V-ing perfect
I could have performed you could have performed he could have performed we could have performed you could have performed they could have performed	I could have been performing you could have been performing he could have been performing we could have been performing you could have been performing they could have been performing

Negation

Simple form	V-ing form
I could not perform you could not perform he could not perform we could not perform you could not perform they could not perform	I could not be performing you could not be performing he could not be performing we could not be performing you could not be performing they could not be performing
Perfect	V-ing perfect
I could not have performed you could not have performed he could not have performed we could not have performed you could not have performed they could not have performed	I could not have been performing you could not have been performing he could not have been performing we could not have been performing you could not have been performing they could not have been performing

Interrogative form

Simple form	V-ing form
could I perform? could you perform? could he perform? could we perform? could you perform? could they perform?	could I be performing? could you be performing? could he be performing? could we be performing? could you be performing? could they be performing?
Perfect	V-ing perfect
could I have performed? could you have performed? could he have performed? could we have performed? could you have performed? could they have performed?	could I have been performing? could you have been performing? could he have been performing? could we have been performing? could you have been performing? could they have been performing?

Interro-negative form

Simple form	V-ing form
could I not perform? could you not perform? could he not perform? could we not perform? could you not perform? could they not perform?	could I not be performing? could you not be performing? could he not be performing? could we not be performing? could you not be performing? could they not be performing?
Perfect	V-ing perfect
could I not have performed? could you not have performed? could he not have performed? could we not have performed? could you not have performed? could they not have performed?	could I not have been performing? could you not have been performing? could he not have been performing? could we not have been performing? could you not have been performing? could they not have been performing?