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 could not decay you could not decay he could not decay we could not decay you could not decay they could not decay	I could not be decaying you could not be decaying he could not be decaying we could not be decaying you could not be decaying they could not be decaying
Perfect	V-ing perfect
I could not have decayed you could not have decayed he could not have decayed we could not have decayed you could not have decayed they could not have decayed	I could not have been decaying you could not have been decaying he could not have been decaying we could not have been decaying you could not have been decaying they could not 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
could I not decay? could you not decay? could he not decay? could we not decay? could you not decay? could they not decay?	could I not be decaying? could you not be decaying? could he not be decaying? could we not be decaying? could you not be decaying? could they not be decaying?
Perfect	V-ing perfect
could I not have decayed? could you not have decayed? could he not have decayed? could we not have decayed? could you not have decayed? could they not have decayed?	could I not have been decaying? could you not have been decaying? could he not have been decaying? could we not have been decaying? could you not have been decaying? could they not have been decaying?