English verb conjugation
COULD HARDEN

Regular verb: harden - hardened - hardened

Affirmation

Simple form	V-ing form
I could harden you could harden he could harden we could harden you could harden they could harden	I could be hardening you could be hardening he could be hardening we could be hardening you could be hardening they could be hardening
Perfect	V-ing perfect
I could have hardened you could have hardened he could have hardened we could have hardened you could have hardened they could have hardened	I could have been hardening you could have been hardening he could have been hardening we could have been hardening you could have been hardening they could have been hardening

Negation

Simple form	V-ing form
I could not harden you could not harden he could not harden we could not harden you could not harden they could not harden	I could not be hardening you could not be hardening he could not be hardening we could not be hardening you could not be hardening they could not be hardening
Perfect	V-ing perfect
I could not have hardened you could not have hardened he could not have hardened we could not have hardened you could not have hardened they could not have hardened	I could not have been hardening you could not have been hardening he could not have been hardening we could not have been hardening you could not have been hardening they could not have been hardening

Interrogative form

Simple form	V-ing form
could I harden? could you harden? could he harden? could we harden? could you harden? could they harden?	could I be hardening? could you be hardening? could he be hardening? could we be hardening? could you be hardening? could they be hardening?
Perfect	V-ing perfect
could I have hardened? could you have hardened? could he have hardened? could we have hardened? could you have hardened? could they have hardened?	could I have been hardening? could you have been hardening? could he have been hardening? could we have been hardening? could you have been hardening? could they have been hardening?

Interro-negative form

Simple form	V-ing form
could I not harden? could you not harden? could he not harden? could we not harden? could you not harden? could they not harden?	could I not be hardening? could you not be hardening? could he not be hardening? could we not be hardening? could you not be hardening? could they not be hardening?
Perfect	V-ing perfect
could I not have hardened? could you not have hardened? could he not have hardened? could we not have hardened? could you not have hardened? could they not have hardened?	could I not have been hardening? could you not have been hardening? could he not have been hardening? could we not have been hardening? could you not have been hardening? could they not have been hardening?