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 can't ventilate you can't ventilate he can't ventilate we can't ventilate you can't ventilate they can't ventilate
V-ing form
I can't be ventilating you can't be ventilating he can't be ventilating we can't be ventilating you can't be ventilating they can't be ventilating
Perfect
I can't have ventilated you can't have ventilated he can't have ventilated we can't have ventilated you can't have ventilated they can't have ventilated
V-ing perfect
I can't have been ventilating you can't have been ventilating he can't have been ventilating we can't have been ventilating you can't have been ventilating they can't 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't I ventilate? can't you ventilate? can't he ventilate? can't we ventilate? can't you ventilate? can't they ventilate?
V-ing form
can't I be ventilating? can't you be ventilating? can't he be ventilating? can't we be ventilating? can't you be ventilating? can't they be ventilating?
Perfect
can't I have ventilated? can't you have ventilated? can't he have ventilated? can't we have ventilated? can't you have ventilated? can't they have ventilated?
V-ing perfect
can't I have been ventilating? can't you have been ventilating? can't he have been ventilating? can't we have been ventilating? can't you have been ventilating? can't they have been ventilating?