English verb conjugation
COULD THICKEN

Regular verb: thicken - thickened - thickened

Affirmation

Simple form	V-ing form
I could thicken you could thicken he could thicken we could thicken you could thicken they could thicken	I could be thickening you could be thickening he could be thickening we could be thickening you could be thickening they could be thickening
Perfect	V-ing perfect
I could have thickened you could have thickened he could have thickened we could have thickened you could have thickened they could have thickened	I could have been thickening you could have been thickening he could have been thickening we could have been thickening you could have been thickening they could have been thickening

Negation

Simple form	V-ing form
I couldn't thicken you couldn't thicken he couldn't thicken we couldn't thicken you couldn't thicken they couldn't thicken	I couldn't be thickening you couldn't be thickening he couldn't be thickening we couldn't be thickening you couldn't be thickening they couldn't be thickening
Perfect	V-ing perfect
I couldn't have thickened you couldn't have thickened he couldn't have thickened we couldn't have thickened you couldn't have thickened they couldn't have thickened	I couldn't have been thickening you couldn't have been thickening he couldn't have been thickening we couldn't have been thickening you couldn't have been thickening they couldn't have been thickening

Interrogative form

Simple form	V-ing form
could I thicken? could you thicken? could he thicken? could we thicken? could you thicken? could they thicken?	could I be thickening? could you be thickening? could he be thickening? could we be thickening? could you be thickening? could they be thickening?
Perfect	V-ing perfect
could I have thickened? could you have thickened? could he have thickened? could we have thickened? could you have thickened? could they have thickened?	could I have been thickening? could you have been thickening? could he have been thickening? could we have been thickening? could you have been thickening? could they have been thickening?

Interro-negative form

Simple form	V-ing form
couldn't I thicken? couldn't you thicken? couldn't he thicken? couldn't we thicken? couldn't you thicken? couldn't they thicken?	couldn't I be thickening? couldn't you be thickening? couldn't he be thickening? couldn't we be thickening? couldn't you be thickening? couldn't they be thickening?
Perfect	V-ing perfect
couldn't I have thickened? couldn't you have thickened? couldn't he have thickened? couldn't we have thickened? couldn't you have thickened? couldn't they have thickened?	couldn't I have been thickening? couldn't you have been thickening? couldn't he have been thickening? couldn't we have been thickening? couldn't you have been thickening? couldn't they have been thickening?