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