English verb conjugation
COULD HOWL

Regular verb: howl - howled - howled

Affirmation

Simple form	V-ing form
I could howl you could howl he could howl we could howl you could howl they could howl	I could be howling you could be howling he could be howling we could be howling you could be howling they could be howling
Perfect	V-ing perfect
I could have howled you could have howled he could have howled we could have howled you could have howled they could have howled	I could have been howling you could have been howling he could have been howling we could have been howling you could have been howling they could have been howling

Negation

Simple form	V-ing form
I could not howl you could not howl he could not howl we could not howl you could not howl they could not howl	I could not be howling you could not be howling he could not be howling we could not be howling you could not be howling they could not be howling
Perfect	V-ing perfect
I could not have howled you could not have howled he could not have howled we could not have howled you could not have howled they could not have howled	I could not have been howling you could not have been howling he could not have been howling we could not have been howling you could not have been howling they could not have been howling

Interrogative form

Simple form	V-ing form
could I howl? could you howl? could he howl? could we howl? could you howl? could they howl?	could I be howling? could you be howling? could he be howling? could we be howling? could you be howling? could they be howling?
Perfect	V-ing perfect
could I have howled? could you have howled? could he have howled? could we have howled? could you have howled? could they have howled?	could I have been howling? could you have been howling? could he have been howling? could we have been howling? could you have been howling? could they have been howling?

Interro-negative form

Simple form	V-ing form
could I not howl? could you not howl? could he not howl? could we not howl? could you not howl? could they not howl?	could I not be howling? could you not be howling? could he not be howling? could we not be howling? could you not be howling? could they not be howling?
Perfect	V-ing perfect
could I not have howled? could you not have howled? could he not have howled? could we not have howled? could you not have howled? could they not have howled?	could I not have been howling? could you not have been howling? could he not have been howling? could we not have been howling? could you not have been howling? could they not have been howling?