English verb conjugation
COULD WINDOW

Regular verb: window - windowed - windowed

Affirmation

Simple form	V-ing form
I could window you could window she could window we could window you could window they could window	I could be windowing you could be windowing she could be windowing we could be windowing you could be windowing they could be windowing
Perfect	V-ing perfect
I could have windowed you could have windowed she could have windowed we could have windowed you could have windowed they could have windowed	I could have been windowing you could have been windowing she could have been windowing we could have been windowing you could have been windowing they could have been windowing

Negation

Simple form	V-ing form
I could not window you could not window she could not window we could not window you could not window they could not window	I could not be windowing you could not be windowing she could not be windowing we could not be windowing you could not be windowing they could not be windowing
Perfect	V-ing perfect
I could not have windowed you could not have windowed she could not have windowed we could not have windowed you could not have windowed they could not have windowed	I could not have been windowing you could not have been windowing she could not have been windowing we could not have been windowing you could not have been windowing they could not have been windowing

Interrogative form

Simple form	V-ing form
could I window? could you window? could she window? could we window? could you window? could they window?	could I be windowing? could you be windowing? could she be windowing? could we be windowing? could you be windowing? could they be windowing?
Perfect	V-ing perfect
could I have windowed? could you have windowed? could she have windowed? could we have windowed? could you have windowed? could they have windowed?	could I have been windowing? could you have been windowing? could she have been windowing? could we have been windowing? could you have been windowing? could they have been windowing?

Interro-negative form

Simple form	V-ing form
could I not window? could you not window? could she not window? could we not window? could you not window? could they not window?	could I not be windowing? could you not be windowing? could she not be windowing? could we not be windowing? could you not be windowing? could they not be windowing?
Perfect	V-ing perfect
could I not have windowed? could you not have windowed? could she not have windowed? could we not have windowed? could you not have windowed? could they not have windowed?	could I not have been windowing? could you not have been windowing? could she not have been windowing? could we not have been windowing? could you not have been windowing? could they not have been windowing?