English verb conjugation
COULD YAK

Regular verb: yak - yaked - yaked

Affirmation

Simple form	V-ing form
I could yak you could yak he could yak we could yak you could yak they could yak	I could be yaking you could be yaking he could be yaking we could be yaking you could be yaking they could be yaking
Perfect	V-ing perfect
I could have yaked you could have yaked he could have yaked we could have yaked you could have yaked they could have yaked	I could have been yaking you could have been yaking he could have been yaking we could have been yaking you could have been yaking they could have been yaking

Negation

Simple form	V-ing form
I couldn't yak you couldn't yak he couldn't yak we couldn't yak you couldn't yak they couldn't yak	I couldn't be yaking you couldn't be yaking he couldn't be yaking we couldn't be yaking you couldn't be yaking they couldn't be yaking
Perfect	V-ing perfect
I couldn't have yaked you couldn't have yaked he couldn't have yaked we couldn't have yaked you couldn't have yaked they couldn't have yaked	I couldn't have been yaking you couldn't have been yaking he couldn't have been yaking we couldn't have been yaking you couldn't have been yaking they couldn't have been yaking

Interrogative form

Simple form	V-ing form
could I yak? could you yak? could he yak? could we yak? could you yak? could they yak?	could I be yaking? could you be yaking? could he be yaking? could we be yaking? could you be yaking? could they be yaking?
Perfect	V-ing perfect
could I have yaked? could you have yaked? could he have yaked? could we have yaked? could you have yaked? could they have yaked?	could I have been yaking? could you have been yaking? could he have been yaking? could we have been yaking? could you have been yaking? could they have been yaking?

Interro-negative form

Simple form	V-ing form
couldn't I yak? couldn't you yak? couldn't he yak? couldn't we yak? couldn't you yak? couldn't they yak?	couldn't I be yaking? couldn't you be yaking? couldn't he be yaking? couldn't we be yaking? couldn't you be yaking? couldn't they be yaking?
Perfect	V-ing perfect
couldn't I have yaked? couldn't you have yaked? couldn't he have yaked? couldn't we have yaked? couldn't you have yaked? couldn't they have yaked?	couldn't I have been yaking? couldn't you have been yaking? couldn't he have been yaking? couldn't we have been yaking? couldn't you have been yaking? couldn't they have been yaking?