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 couldn't window you couldn't window she couldn't window we couldn't window you couldn't window they couldn't window	I couldn't be windowing you couldn't be windowing she couldn't be windowing we couldn't be windowing you couldn't be windowing they couldn't be windowing
Perfect	V-ing perfect
I couldn't have windowed you couldn't have windowed she couldn't have windowed we couldn't have windowed you couldn't have windowed they couldn't have windowed	I couldn't have been windowing you couldn't have been windowing she couldn't have been windowing we couldn't have been windowing you couldn't have been windowing they couldn't 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
couldn't I window? couldn't you window? couldn't she window? couldn't we window? couldn't you window? couldn't they window?	couldn't I be windowing? couldn't you be windowing? couldn't she be windowing? couldn't we be windowing? couldn't you be windowing? couldn't they be windowing?
Perfect	V-ing perfect
couldn't I have windowed? couldn't you have windowed? couldn't she have windowed? couldn't we have windowed? couldn't you have windowed? couldn't they have windowed?	couldn't I have been windowing? couldn't you have been windowing? couldn't she have been windowing? couldn't we have been windowing? couldn't you have been windowing? couldn't they have been windowing?