English verb conjugation
COULD TARNISH

Regular verb: tarnish - tarnished - tarnished

Affirmation

Simple form	V-ing form
I could tarnish you could tarnish he could tarnish we could tarnish you could tarnish they could tarnish	I could be tarnishing you could be tarnishing he 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 he 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 he 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 he 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 he 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 he 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 he 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 he tarnish? could we tarnish? could you tarnish? could they tarnish?	could I be tarnishing? could you be tarnishing? could he 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 he 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 he 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 he 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 he 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 he 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 he have been tarnishing? couldn't we have been tarnishing? couldn't you have been tarnishing? couldn't they have been tarnishing?