could yap
Regular verb: yap - yapped- yapped

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could yap
you could yap
he could yap
we could yap
you could yap
they could yap 	I could be yapping
you could be yapping
he could be yapping
we could be yapping
you could be yapping
they could be yapping	I could have yapped
you could have yapped
he could have yapped
we could have yapped
you could have yapped
they could have yapped	I could have been yapping
you could have been yapping
he could have been yapping
we could have been yapping
you could have been yapping
they could have been yapping	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could not yap
you could not yap
he could not yap
we could not yap
you could not yap
they could not yap 	I could not be yapping
you could not be yapping
he could not be yapping
we could not be yapping
you could not be yapping
they could not be yapping	I could not have yapped
you could not have yapped
he could not have yapped
we could not have yapped
you could not have yapped
they could not have yapped	I could not have been yapping
you could not have been yapping
he could not have been yapping
we could not have been yapping
you could not have been yapping
they could not have been yapping	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I yap?
could you yap?
could he yap?
could we yap?
could you yap?
could they yap? 	could I be yapping?
could you be yapping?
could he be yapping?
could we be yapping?
could you be yapping?
could they be yapping? 	could I have yapped?
could you have yapped?
could he have yapped?
could we have yapped?
could you have yapped?
could they have yapped? 	could I have been yapping?
could you have been yapping?
could he have been yapping?
could we have been yapping?
could you have been yapping?
could they have been yapping? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I not yap?
could you not yap?
could he not yap?
could we not yap?
could you not yap?
could they not yap? 	could I not be yapping?
could you not be yapping?
could he not be yapping?
could we not be yapping?
could you not be yapping?
could they not be yapping? 	could I not have yapped?
could you not have yapped?
could he not have yapped?
could we not have yapped?
could you not have yapped?
could they not have yapped? 	could I not have been yapping?
could you not have been yapping?
could he not have been yapping?
could we not have been yapping?
could you not have been yapping?
could they not have been yapping?