English verb conjugation
COULD DECAY

Regular verb: decay - decayed - decayed

Affirmation

Simple form	V-ing form
I could decay you could decay he could decay we could decay you could decay they could decay	I could be decaying you could be decaying he could be decaying we could be decaying you could be decaying they could be decaying
Perfect	V-ing perfect
I could have decayed you could have decayed he could have decayed we could have decayed you could have decayed they could have decayed	I could have been decaying you could have been decaying he could have been decaying we could have been decaying you could have been decaying they could have been decaying

Negation

Simple form	V-ing form
I couldn't decay you couldn't decay he couldn't decay we couldn't decay you couldn't decay they couldn't decay	I couldn't be decaying you couldn't be decaying he couldn't be decaying we couldn't be decaying you couldn't be decaying they couldn't be decaying
Perfect	V-ing perfect
I couldn't have decayed you couldn't have decayed he couldn't have decayed we couldn't have decayed you couldn't have decayed they couldn't have decayed	I couldn't have been decaying you couldn't have been decaying he couldn't have been decaying we couldn't have been decaying you couldn't have been decaying they couldn't have been decaying

Interrogative form

Simple form	V-ing form
could I decay? could you decay? could he decay? could we decay? could you decay? could they decay?	could I be decaying? could you be decaying? could he be decaying? could we be decaying? could you be decaying? could they be decaying?
Perfect	V-ing perfect
could I have decayed? could you have decayed? could he have decayed? could we have decayed? could you have decayed? could they have decayed?	could I have been decaying? could you have been decaying? could he have been decaying? could we have been decaying? could you have been decaying? could they have been decaying?

Interro-negative form

Simple form	V-ing form
couldn't I decay? couldn't you decay? couldn't he decay? couldn't we decay? couldn't you decay? couldn't they decay?	couldn't I be decaying? couldn't you be decaying? couldn't he be decaying? couldn't we be decaying? couldn't you be decaying? couldn't they be decaying?
Perfect	V-ing perfect
couldn't I have decayed? couldn't you have decayed? couldn't he have decayed? couldn't we have decayed? couldn't you have decayed? couldn't they have decayed?	couldn't I have been decaying? couldn't you have been decaying? couldn't he have been decaying? couldn't we have been decaying? couldn't you have been decaying? couldn't they have been decaying?