could yackety-yack
Regular verb: yackety-yack - yackety-yacked- yackety-yacked

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could yackety-yack
you could yackety-yack
she could yackety-yack
we could yackety-yack
you could yackety-yack
they could yackety-yack 	I could be yackety-yacking
you could be yackety-yacking
she could be yackety-yacking
we could be yackety-yacking
you could be yackety-yacking
they could be yackety-yacking	I could have yackety-yacked
you could have yackety-yacked
she could have yackety-yacked
we could have yackety-yacked
you could have yackety-yacked
they could have yackety-yacked	I could have been yackety-yacking
you could have been yackety-yacking
she could have been yackety-yacking
we could have been yackety-yacking
you could have been yackety-yacking
they could have been yackety-yacking	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't yackety-yack
you couldn't yackety-yack
she couldn't yackety-yack
we couldn't yackety-yack
you couldn't yackety-yack
they couldn't yackety-yack 	I couldn't be yackety-yacking
you couldn't be yackety-yacking
she couldn't be yackety-yacking
we couldn't be yackety-yacking
you couldn't be yackety-yacking
they couldn't be yackety-yacking	I couldn't have yackety-yacked
you couldn't have yackety-yacked
she couldn't have yackety-yacked
we couldn't have yackety-yacked
you couldn't have yackety-yacked
they couldn't have yackety-yacked	I couldn't have been yackety-yacking
you couldn't have been yackety-yacking
she couldn't have been yackety-yacking
we couldn't have been yackety-yacking
you couldn't have been yackety-yacking
they couldn't have been yackety-yacking	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I yackety-yack?
could you yackety-yack?
could she yackety-yack?
could we yackety-yack?
could you yackety-yack?
could they yackety-yack? 	could I be yackety-yacking?
could you be yackety-yacking?
could she be yackety-yacking?
could we be yackety-yacking?
could you be yackety-yacking?
could they be yackety-yacking? 	could I have yackety-yacked?
could you have yackety-yacked?
could she have yackety-yacked?
could we have yackety-yacked?
could you have yackety-yacked?
could they have yackety-yacked? 	could I have been yackety-yacking?
could you have been yackety-yacking?
could she have been yackety-yacking?
could we have been yackety-yacking?
could you have been yackety-yacking?
could they have been yackety-yacking? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I yackety-yack?
couldn't you yackety-yack?
couldn't she yackety-yack?
couldn't we yackety-yack?
couldn't you yackety-yack?
couldn't they yackety-yack? 	couldn't I be yackety-yacking?
couldn't you be yackety-yacking?
couldn't she be yackety-yacking?
couldn't we be yackety-yacking?
couldn't you be yackety-yacking?
couldn't they be yackety-yacking? 	couldn't I have yackety-yacked?
couldn't you have yackety-yacked?
couldn't she have yackety-yacked?
couldn't we have yackety-yacked?
couldn't you have yackety-yacked?
couldn't they have yackety-yacked? 	couldn't I have been yackety-yacking?
couldn't you have been yackety-yacking?
couldn't she have been yackety-yacking?
couldn't we have been yackety-yacking?
couldn't you have been yackety-yacking?
couldn't they have been yackety-yacking?