English verb conjugation
COULD YES

Regular verb: yes - yesed - yesed

Affirmation

Simple form	V-ing form
I could yes you could yes he could yes we could yes you could yes they could yes	I could be yesing you could be yesing he could be yesing we could be yesing you could be yesing they could be yesing
Perfect	V-ing perfect
I could have yesed you could have yesed he could have yesed we could have yesed you could have yesed they could have yesed	I could have been yesing you could have been yesing he could have been yesing we could have been yesing you could have been yesing they could have been yesing

Negation

Simple form	V-ing form
I couldn't yes you couldn't yes he couldn't yes we couldn't yes you couldn't yes they couldn't yes	I couldn't be yesing you couldn't be yesing he couldn't be yesing we couldn't be yesing you couldn't be yesing they couldn't be yesing
Perfect	V-ing perfect
I couldn't have yesed you couldn't have yesed he couldn't have yesed we couldn't have yesed you couldn't have yesed they couldn't have yesed	I couldn't have been yesing you couldn't have been yesing he couldn't have been yesing we couldn't have been yesing you couldn't have been yesing they couldn't have been yesing

Interrogative form

Simple form	V-ing form
could I yes? could you yes? could he yes? could we yes? could you yes? could they yes?	could I be yesing? could you be yesing? could he be yesing? could we be yesing? could you be yesing? could they be yesing?
Perfect	V-ing perfect
could I have yesed? could you have yesed? could he have yesed? could we have yesed? could you have yesed? could they have yesed?	could I have been yesing? could you have been yesing? could he have been yesing? could we have been yesing? could you have been yesing? could they have been yesing?

Interro-negative form

Simple form	V-ing form
couldn't I yes? couldn't you yes? couldn't he yes? couldn't we yes? couldn't you yes? couldn't they yes?	couldn't I be yesing? couldn't you be yesing? couldn't he be yesing? couldn't we be yesing? couldn't you be yesing? couldn't they be yesing?
Perfect	V-ing perfect
couldn't I have yesed? couldn't you have yesed? couldn't he have yesed? couldn't we have yesed? couldn't you have yesed? couldn't they have yesed?	couldn't I have been yesing? couldn't you have been yesing? couldn't he have been yesing? couldn't we have been yesing? couldn't you have been yesing? couldn't they have been yesing?