English verb conjugation
COULD UNTHREAD

Regular verb: unthread - unthreaded - unthreaded

Affirmation

Simple form	V-ing form
I could unthread you could unthread he could unthread we could unthread you could unthread they could unthread	I could be unthreading you could be unthreading he could be unthreading we could be unthreading you could be unthreading they could be unthreading
Perfect	V-ing perfect
I could have unthreaded you could have unthreaded he could have unthreaded we could have unthreaded you could have unthreaded they could have unthreaded	I could have been unthreading you could have been unthreading he could have been unthreading we could have been unthreading you could have been unthreading they could have been unthreading

Negation

Simple form	V-ing form
I couldn't unthread you couldn't unthread he couldn't unthread we couldn't unthread you couldn't unthread they couldn't unthread	I couldn't be unthreading you couldn't be unthreading he couldn't be unthreading we couldn't be unthreading you couldn't be unthreading they couldn't be unthreading
Perfect	V-ing perfect
I couldn't have unthreaded you couldn't have unthreaded he couldn't have unthreaded we couldn't have unthreaded you couldn't have unthreaded they couldn't have unthreaded	I couldn't have been unthreading you couldn't have been unthreading he couldn't have been unthreading we couldn't have been unthreading you couldn't have been unthreading they couldn't have been unthreading

Interrogative form

Simple form	V-ing form
could I unthread? could you unthread? could he unthread? could we unthread? could you unthread? could they unthread?	could I be unthreading? could you be unthreading? could he be unthreading? could we be unthreading? could you be unthreading? could they be unthreading?
Perfect	V-ing perfect
could I have unthreaded? could you have unthreaded? could he have unthreaded? could we have unthreaded? could you have unthreaded? could they have unthreaded?	could I have been unthreading? could you have been unthreading? could he have been unthreading? could we have been unthreading? could you have been unthreading? could they have been unthreading?

Interro-negative form

Simple form	V-ing form
couldn't I unthread? couldn't you unthread? couldn't he unthread? couldn't we unthread? couldn't you unthread? couldn't they unthread?	couldn't I be unthreading? couldn't you be unthreading? couldn't he be unthreading? couldn't we be unthreading? couldn't you be unthreading? couldn't they be unthreading?
Perfect	V-ing perfect
couldn't I have unthreaded? couldn't you have unthreaded? couldn't he have unthreaded? couldn't we have unthreaded? couldn't you have unthreaded? couldn't they have unthreaded?	couldn't I have been unthreading? couldn't you have been unthreading? couldn't he have been unthreading? couldn't we have been unthreading? couldn't you have been unthreading? couldn't they have been unthreading?