English verb conjugation
COULD SIRE

Regular verb: sire - sired - sired

Affirmation

Simple form	V-ing form
I could sire you could sire she could sire we could sire you could sire they could sire	I could be siring you could be siring she could be siring we could be siring you could be siring they could be siring
Perfect	V-ing perfect
I could have sired you could have sired she could have sired we could have sired you could have sired they could have sired	I could have been siring you could have been siring she could have been siring we could have been siring you could have been siring they could have been siring

Negation

Simple form	V-ing form
I couldn't sire you couldn't sire she couldn't sire we couldn't sire you couldn't sire they couldn't sire	I couldn't be siring you couldn't be siring she couldn't be siring we couldn't be siring you couldn't be siring they couldn't be siring
Perfect	V-ing perfect
I couldn't have sired you couldn't have sired she couldn't have sired we couldn't have sired you couldn't have sired they couldn't have sired	I couldn't have been siring you couldn't have been siring she couldn't have been siring we couldn't have been siring you couldn't have been siring they couldn't have been siring

Interrogative form

Simple form	V-ing form
could I sire? could you sire? could she sire? could we sire? could you sire? could they sire?	could I be siring? could you be siring? could she be siring? could we be siring? could you be siring? could they be siring?
Perfect	V-ing perfect
could I have sired? could you have sired? could she have sired? could we have sired? could you have sired? could they have sired?	could I have been siring? could you have been siring? could she have been siring? could we have been siring? could you have been siring? could they have been siring?

Interro-negative form

Simple form	V-ing form
couldn't I sire? couldn't you sire? couldn't she sire? couldn't we sire? couldn't you sire? couldn't they sire?	couldn't I be siring? couldn't you be siring? couldn't she be siring? couldn't we be siring? couldn't you be siring? couldn't they be siring?
Perfect	V-ing perfect
couldn't I have sired? couldn't you have sired? couldn't she have sired? couldn't we have sired? couldn't you have sired? couldn't they have sired?	couldn't I have been siring? couldn't you have been siring? couldn't she have been siring? couldn't we have been siring? couldn't you have been siring? couldn't they have been siring?