English verb conjugation
COULD TARNISH

Regular verb: tarnish - tarnished - tarnished

Affirmation

Simple form	V-ing form
I could tarnish you could tarnish she could tarnish we could tarnish you could tarnish they could tarnish	I could be tarnishing you could be tarnishing she could be tarnishing we could be tarnishing you could be tarnishing they could be tarnishing
Perfect	V-ing perfect
I could have tarnished you could have tarnished she could have tarnished we could have tarnished you could have tarnished they could have tarnished	I could have been tarnishing you could have been tarnishing she could have been tarnishing we could have been tarnishing you could have been tarnishing they could have been tarnishing

Negation

Simple form	V-ing form
I couldn't tarnish you couldn't tarnish she couldn't tarnish we couldn't tarnish you couldn't tarnish they couldn't tarnish	I couldn't be tarnishing you couldn't be tarnishing she couldn't be tarnishing we couldn't be tarnishing you couldn't be tarnishing they couldn't be tarnishing
Perfect	V-ing perfect
I couldn't have tarnished you couldn't have tarnished she couldn't have tarnished we couldn't have tarnished you couldn't have tarnished they couldn't have tarnished	I couldn't have been tarnishing you couldn't have been tarnishing she couldn't have been tarnishing we couldn't have been tarnishing you couldn't have been tarnishing they couldn't have been tarnishing

Interrogative form

Simple form	V-ing form
could I tarnish? could you tarnish? could she tarnish? could we tarnish? could you tarnish? could they tarnish?	could I be tarnishing? could you be tarnishing? could she be tarnishing? could we be tarnishing? could you be tarnishing? could they be tarnishing?
Perfect	V-ing perfect
could I have tarnished? could you have tarnished? could she have tarnished? could we have tarnished? could you have tarnished? could they have tarnished?	could I have been tarnishing? could you have been tarnishing? could she have been tarnishing? could we have been tarnishing? could you have been tarnishing? could they have been tarnishing?

Interro-negative form

Simple form	V-ing form
couldn't I tarnish? couldn't you tarnish? couldn't she tarnish? couldn't we tarnish? couldn't you tarnish? couldn't they tarnish?	couldn't I be tarnishing? couldn't you be tarnishing? couldn't she be tarnishing? couldn't we be tarnishing? couldn't you be tarnishing? couldn't they be tarnishing?
Perfect	V-ing perfect
couldn't I have tarnished? couldn't you have tarnished? couldn't she have tarnished? couldn't we have tarnished? couldn't you have tarnished? couldn't they have tarnished?	couldn't I have been tarnishing? couldn't you have been tarnishing? couldn't she have been tarnishing? couldn't we have been tarnishing? couldn't you have been tarnishing? couldn't they have been tarnishing?