English verb conjugation
COULD YIP

Regular verb: yip - yipped - yipped

Affirmation

Simple form	V-ing form
I could yip you could yip she could yip we could yip you could yip they could yip	I could be yipping you could be yipping she could be yipping we could be yipping you could be yipping they could be yipping
Perfect	V-ing perfect
I could have yipped you could have yipped she could have yipped we could have yipped you could have yipped they could have yipped	I could have been yipping you could have been yipping she could have been yipping we could have been yipping you could have been yipping they could have been yipping

Negation

Simple form	V-ing form
I could not yip you could not yip she could not yip we could not yip you could not yip they could not yip	I could not be yipping you could not be yipping she could not be yipping we could not be yipping you could not be yipping they could not be yipping
Perfect	V-ing perfect
I could not have yipped you could not have yipped she could not have yipped we could not have yipped you could not have yipped they could not have yipped	I could not have been yipping you could not have been yipping she could not have been yipping we could not have been yipping you could not have been yipping they could not have been yipping

Interrogative form

Simple form	V-ing form
could I yip? could you yip? could she yip? could we yip? could you yip? could they yip?	could I be yipping? could you be yipping? could she be yipping? could we be yipping? could you be yipping? could they be yipping?
Perfect	V-ing perfect
could I have yipped? could you have yipped? could she have yipped? could we have yipped? could you have yipped? could they have yipped?	could I have been yipping? could you have been yipping? could she have been yipping? could we have been yipping? could you have been yipping? could they have been yipping?

Interro-negative form

Simple form	V-ing form
could I not yip? could you not yip? could she not yip? could we not yip? could you not yip? could they not yip?	could I not be yipping? could you not be yipping? could she not be yipping? could we not be yipping? could you not be yipping? could they not be yipping?
Perfect	V-ing perfect
could I not have yipped? could you not have yipped? could she not have yipped? could we not have yipped? could you not have yipped? could they not have yipped?	could I not have been yipping? could you not have been yipping? could she not have been yipping? could we not have been yipping? could you not have been yipping? could they not have been yipping?