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 couldn't harden you couldn't harden he couldn't harden we couldn't harden you couldn't harden they couldn't harden	I couldn't be hardening you couldn't be hardening he couldn't be hardening we couldn't be hardening you couldn't be hardening they couldn't be hardening
Perfect	V-ing perfect
I couldn't have hardened you couldn't have hardened he couldn't have hardened we couldn't have hardened you couldn't have hardened they couldn't have hardened	I couldn't have been hardening you couldn't have been hardening he couldn't have been hardening we couldn't have been hardening you couldn't have been hardening they couldn't 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
couldn't I harden? couldn't you harden? couldn't he harden? couldn't we harden? couldn't you harden? couldn't they harden?	couldn't I be hardening? couldn't you be hardening? couldn't he be hardening? couldn't we be hardening? couldn't you be hardening? couldn't they be hardening?
Perfect	V-ing perfect
couldn't I have hardened? couldn't you have hardened? couldn't he have hardened? couldn't we have hardened? couldn't you have hardened? couldn't they have hardened?	couldn't I have been hardening? couldn't you have been hardening? couldn't he have been hardening? couldn't we have been hardening? couldn't you have been hardening? couldn't they have been hardening?