I can ventilate you can ventilate he can ventilate we can ventilate you can ventilate they can ventilate
V-ing form
I can be ventilating you can be ventilating he can be ventilating we can be ventilating you can be ventilating they can be ventilating
Perfect
I can have ventilated you can have ventilated he can have ventilated we can have ventilated you can have ventilated they can have ventilated
V-ing perfect
I can have been ventilating you can have been ventilating he can have been ventilating we can have been ventilating you can have been ventilating they can have been ventilating
Negation
Simple form
I cannot ventilate you cannot ventilate he cannot ventilate we cannot ventilate you cannot ventilate they cannot ventilate
V-ing form
I cannot be ventilating you cannot be ventilating he cannot be ventilating we cannot be ventilating you cannot be ventilating they cannot be ventilating
Perfect
I cannot have ventilated you cannot have ventilated he cannot have ventilated we cannot have ventilated you cannot have ventilated they cannot have ventilated
V-ing perfect
I cannot have been ventilating you cannot have been ventilating he cannot have been ventilating we cannot have been ventilating you cannot have been ventilating they cannot have been ventilating
Interrogative form
Simple form
can I ventilate? can you ventilate? can he ventilate? can we ventilate? can you ventilate? can they ventilate?
V-ing form
can I be ventilating? can you be ventilating? can he be ventilating? can we be ventilating? can you be ventilating? can they be ventilating?
Perfect
can I have ventilated? can you have ventilated? can he have ventilated? can we have ventilated? can you have ventilated? can they have ventilated?
V-ing perfect
can I have been ventilating? can you have been ventilating? can he have been ventilating? can we have been ventilating? can you have been ventilating? can they have been ventilating?
Interro-negative form
Simple form
can I not ventilate? can you not ventilate? can he not ventilate? can we not ventilate? can you not ventilate? can they not ventilate?
V-ing form
can I not be ventilating? can you not be ventilating? can he not be ventilating? can we not be ventilating? can you not be ventilating? can they not be ventilating?
Perfect
can I not have ventilated? can you not have ventilated? can he not have ventilated? can we not have ventilated? can you not have ventilated? can they not have ventilated?
V-ing perfect
can I not have been ventilating? can you not have been ventilating? can he not have been ventilating? can we not have been ventilating? can you not have been ventilating? can they not have been ventilating?