English verb conjugation
COULD HISS

Regular verb: hiss - hissed - hissed

Affirmation

Simple form	V-ing form
I could hiss you could hiss he could hiss we could hiss you could hiss they could hiss	I could be hissing you could be hissing he could be hissing we could be hissing you could be hissing they could be hissing
Perfect	V-ing perfect
I could have hissed you could have hissed he could have hissed we could have hissed you could have hissed they could have hissed	I could have been hissing you could have been hissing he could have been hissing we could have been hissing you could have been hissing they could have been hissing

Negation

Simple form	V-ing form
I couldn't hiss you couldn't hiss he couldn't hiss we couldn't hiss you couldn't hiss they couldn't hiss	I couldn't be hissing you couldn't be hissing he couldn't be hissing we couldn't be hissing you couldn't be hissing they couldn't be hissing
Perfect	V-ing perfect
I couldn't have hissed you couldn't have hissed he couldn't have hissed we couldn't have hissed you couldn't have hissed they couldn't have hissed	I couldn't have been hissing you couldn't have been hissing he couldn't have been hissing we couldn't have been hissing you couldn't have been hissing they couldn't have been hissing

Interrogative form

Simple form	V-ing form
could I hiss? could you hiss? could he hiss? could we hiss? could you hiss? could they hiss?	could I be hissing? could you be hissing? could he be hissing? could we be hissing? could you be hissing? could they be hissing?
Perfect	V-ing perfect
could I have hissed? could you have hissed? could he have hissed? could we have hissed? could you have hissed? could they have hissed?	could I have been hissing? could you have been hissing? could he have been hissing? could we have been hissing? could you have been hissing? could they have been hissing?

Interro-negative form

Simple form	V-ing form
couldn't I hiss? couldn't you hiss? couldn't he hiss? couldn't we hiss? couldn't you hiss? couldn't they hiss?	couldn't I be hissing? couldn't you be hissing? couldn't he be hissing? couldn't we be hissing? couldn't you be hissing? couldn't they be hissing?
Perfect	V-ing perfect
couldn't I have hissed? couldn't you have hissed? couldn't he have hissed? couldn't we have hissed? couldn't you have hissed? couldn't they have hissed?	couldn't I have been hissing? couldn't you have been hissing? couldn't he have been hissing? couldn't we have been hissing? couldn't you have been hissing? couldn't they have been hissing?