English verb conjugation
COULD YELP

Regular verb: yelp - yelped - yelped

Affirmation

Simple form	V-ing form
I could yelp you could yelp he could yelp we could yelp you could yelp they could yelp	I could be yelping you could be yelping he could be yelping we could be yelping you could be yelping they could be yelping
Perfect	V-ing perfect
I could have yelped you could have yelped he could have yelped we could have yelped you could have yelped they could have yelped	I could have been yelping you could have been yelping he could have been yelping we could have been yelping you could have been yelping they could have been yelping

Negation

Simple form	V-ing form
I couldn't yelp you couldn't yelp he couldn't yelp we couldn't yelp you couldn't yelp they couldn't yelp	I couldn't be yelping you couldn't be yelping he couldn't be yelping we couldn't be yelping you couldn't be yelping they couldn't be yelping
Perfect	V-ing perfect
I couldn't have yelped you couldn't have yelped he couldn't have yelped we couldn't have yelped you couldn't have yelped they couldn't have yelped	I couldn't have been yelping you couldn't have been yelping he couldn't have been yelping we couldn't have been yelping you couldn't have been yelping they couldn't have been yelping

Interrogative form

Simple form	V-ing form
could I yelp? could you yelp? could he yelp? could we yelp? could you yelp? could they yelp?	could I be yelping? could you be yelping? could he be yelping? could we be yelping? could you be yelping? could they be yelping?
Perfect	V-ing perfect
could I have yelped? could you have yelped? could he have yelped? could we have yelped? could you have yelped? could they have yelped?	could I have been yelping? could you have been yelping? could he have been yelping? could we have been yelping? could you have been yelping? could they have been yelping?

Interro-negative form

Simple form	V-ing form
couldn't I yelp? couldn't you yelp? couldn't he yelp? couldn't we yelp? couldn't you yelp? couldn't they yelp?	couldn't I be yelping? couldn't you be yelping? couldn't he be yelping? couldn't we be yelping? couldn't you be yelping? couldn't they be yelping?
Perfect	V-ing perfect
couldn't I have yelped? couldn't you have yelped? couldn't he have yelped? couldn't we have yelped? couldn't you have yelped? couldn't they have yelped?	couldn't I have been yelping? couldn't you have been yelping? couldn't he have been yelping? couldn't we have been yelping? couldn't you have been yelping? couldn't they have been yelping?