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 couldn't yip you couldn't yip she couldn't yip we couldn't yip you couldn't yip they couldn't yip	I couldn't be yipping you couldn't be yipping she couldn't be yipping we couldn't be yipping you couldn't be yipping they couldn't be yipping
Perfect	V-ing perfect
I couldn't have yipped you couldn't have yipped she couldn't have yipped we couldn't have yipped you couldn't have yipped they couldn't have yipped	I couldn't have been yipping you couldn't have been yipping she couldn't have been yipping we couldn't have been yipping you couldn't have been yipping they couldn't 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
couldn't I yip? couldn't you yip? couldn't she yip? couldn't we yip? couldn't you yip? couldn't they yip?	couldn't I be yipping? couldn't you be yipping? couldn't she be yipping? couldn't we be yipping? couldn't you be yipping? couldn't they be yipping?
Perfect	V-ing perfect
couldn't I have yipped? couldn't you have yipped? couldn't she have yipped? couldn't we have yipped? couldn't you have yipped? couldn't they have yipped?	couldn't I have been yipping? couldn't you have been yipping? couldn't she have been yipping? couldn't we have been yipping? couldn't you have been yipping? couldn't they have been yipping?