English verb conjugation
COULD HISS

Regular verb: hiss - hissed - hissed

Affirmation

Simple form	V-ing form
I could hiss you could hiss she could hiss we could hiss you could hiss they could hiss	I could be hissing you could be hissing she 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 she 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 she 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 could not hiss you could not hiss she could not hiss we could not hiss you could not hiss they could not hiss	I could not be hissing you could not be hissing she could not be hissing we could not be hissing you could not be hissing they could not be hissing
Perfect	V-ing perfect
I could not have hissed you could not have hissed she could not have hissed we could not have hissed you could not have hissed they could not have hissed	I could not have been hissing you could not have been hissing she could not have been hissing we could not have been hissing you could not have been hissing they could not have been hissing

Interrogative form

Simple form	V-ing form
could I hiss? could you hiss? could she hiss? could we hiss? could you hiss? could they hiss?	could I be hissing? could you be hissing? could she 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 she 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 she 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
could I not hiss? could you not hiss? could she not hiss? could we not hiss? could you not hiss? could they not hiss?	could I not be hissing? could you not be hissing? could she not be hissing? could we not be hissing? could you not be hissing? could they not be hissing?
Perfect	V-ing perfect
could I not have hissed? could you not have hissed? could she not have hissed? could we not have hissed? could you not have hissed? could they not have hissed?	could I not have been hissing? could you not have been hissing? could she not have been hissing? could we not have been hissing? could you not have been hissing? could they not have been hissing?