English verb conjugation
COULD BILLOW

Regular verb: billow - billowed - billowed

Affirmation

Simple form	V-ing form
I could billow you could billow she could billow we could billow you could billow they could billow	I could be billowing you could be billowing she could be billowing we could be billowing you could be billowing they could be billowing
Perfect	V-ing perfect
I could have billowed you could have billowed she could have billowed we could have billowed you could have billowed they could have billowed	I could have been billowing you could have been billowing she could have been billowing we could have been billowing you could have been billowing they could have been billowing

Negation

Simple form	V-ing form
I couldn't billow you couldn't billow she couldn't billow we couldn't billow you couldn't billow they couldn't billow	I couldn't be billowing you couldn't be billowing she couldn't be billowing we couldn't be billowing you couldn't be billowing they couldn't be billowing
Perfect	V-ing perfect
I couldn't have billowed you couldn't have billowed she couldn't have billowed we couldn't have billowed you couldn't have billowed they couldn't have billowed	I couldn't have been billowing you couldn't have been billowing she couldn't have been billowing we couldn't have been billowing you couldn't have been billowing they couldn't have been billowing

Interrogative form

Simple form	V-ing form
could I billow? could you billow? could she billow? could we billow? could you billow? could they billow?	could I be billowing? could you be billowing? could she be billowing? could we be billowing? could you be billowing? could they be billowing?
Perfect	V-ing perfect
could I have billowed? could you have billowed? could she have billowed? could we have billowed? could you have billowed? could they have billowed?	could I have been billowing? could you have been billowing? could she have been billowing? could we have been billowing? could you have been billowing? could they have been billowing?

Interro-negative form

Simple form	V-ing form
couldn't I billow? couldn't you billow? couldn't she billow? couldn't we billow? couldn't you billow? couldn't they billow?	couldn't I be billowing? couldn't you be billowing? couldn't she be billowing? couldn't we be billowing? couldn't you be billowing? couldn't they be billowing?
Perfect	V-ing perfect
couldn't I have billowed? couldn't you have billowed? couldn't she have billowed? couldn't we have billowed? couldn't you have billowed? couldn't they have billowed?	couldn't I have been billowing? couldn't you have been billowing? couldn't she have been billowing? couldn't we have been billowing? couldn't you have been billowing? couldn't they have been billowing?