I can window you can window he can window we can window you can window they can window
V-ing form
I can be windowing you can be windowing he can be windowing we can be windowing you can be windowing they can be windowing
Perfect
I can have windowed you can have windowed he can have windowed we can have windowed you can have windowed they can have windowed
V-ing perfect
I can have been windowing you can have been windowing he can have been windowing we can have been windowing you can have been windowing they can have been windowing
Negation
Simple form
I cannot window you cannot window he cannot window we cannot window you cannot window they cannot window
V-ing form
I cannot be windowing you cannot be windowing he cannot be windowing we cannot be windowing you cannot be windowing they cannot be windowing
Perfect
I cannot have windowed you cannot have windowed he cannot have windowed we cannot have windowed you cannot have windowed they cannot have windowed
V-ing perfect
I cannot have been windowing you cannot have been windowing he cannot have been windowing we cannot have been windowing you cannot have been windowing they cannot have been windowing
Interrogative form
Simple form
can I window? can you window? can he window? can we window? can you window? can they window?
V-ing form
can I be windowing? can you be windowing? can he be windowing? can we be windowing? can you be windowing? can they be windowing?
Perfect
can I have windowed? can you have windowed? can he have windowed? can we have windowed? can you have windowed? can they have windowed?
V-ing perfect
can I have been windowing? can you have been windowing? can he have been windowing? can we have been windowing? can you have been windowing? can they have been windowing?
Interro-negative form
Simple form
can I not window? can you not window? can he not window? can we not window? can you not window? can they not window?
V-ing form
can I not be windowing? can you not be windowing? can he not be windowing? can we not be windowing? can you not be windowing? can they not be windowing?
Perfect
can I not have windowed? can you not have windowed? can he not have windowed? can we not have windowed? can you not have windowed? can they not have windowed?
V-ing perfect
can I not have been windowing? can you not have been windowing? can he not have been windowing? can we not have been windowing? can you not have been windowing? can they not have been windowing?