Warning, this verb may not exist. Conjugation is given as example.
Affirmation
Simple form
I could unwash you could unwash he could unwash we could unwash you could unwash they could unwash
V-ing form
I could be unwashing you could be unwashing he could be unwashing we could be unwashing you could be unwashing they could be unwashing
Perfect
I could have unwashed you could have unwashed he could have unwashed we could have unwashed you could have unwashed they could have unwashed
V-ing perfect
I could have been unwashing you could have been unwashing he could have been unwashing we could have been unwashing you could have been unwashing they could have been unwashing
Negation
Simple form
I couldn't unwash you couldn't unwash he couldn't unwash we couldn't unwash you couldn't unwash they couldn't unwash
V-ing form
I couldn't be unwashing you couldn't be unwashing he couldn't be unwashing we couldn't be unwashing you couldn't be unwashing they couldn't be unwashing
Perfect
I couldn't have unwashed you couldn't have unwashed he couldn't have unwashed we couldn't have unwashed you couldn't have unwashed they couldn't have unwashed
V-ing perfect
I couldn't have been unwashing you couldn't have been unwashing he couldn't have been unwashing we couldn't have been unwashing you couldn't have been unwashing they couldn't have been unwashing
Interrogative form
Simple form
could I unwash? could you unwash? could he unwash? could we unwash? could you unwash? could they unwash?
V-ing form
could I be unwashing? could you be unwashing? could he be unwashing? could we be unwashing? could you be unwashing? could they be unwashing?
Perfect
could I have unwashed? could you have unwashed? could he have unwashed? could we have unwashed? could you have unwashed? could they have unwashed?
V-ing perfect
could I have been unwashing? could you have been unwashing? could he have been unwashing? could we have been unwashing? could you have been unwashing? could they have been unwashing?
Interro-negative form
Simple form
couldn't I unwash? couldn't you unwash? couldn't he unwash? couldn't we unwash? couldn't you unwash? couldn't they unwash?
V-ing form
couldn't I be unwashing? couldn't you be unwashing? couldn't he be unwashing? couldn't we be unwashing? couldn't you be unwashing? couldn't they be unwashing?
Perfect
couldn't I have unwashed? couldn't you have unwashed? couldn't he have unwashed? couldn't we have unwashed? couldn't you have unwashed? couldn't they have unwashed?
V-ing perfect
couldn't I have been unwashing? couldn't you have been unwashing? couldn't he have been unwashing? couldn't we have been unwashing? couldn't you have been unwashing? couldn't they have been unwashing?