I can heighten you can heighten he can heighten we can heighten you can heighten they can heighten
V-ing form
I can be heightening you can be heightening he can be heightening we can be heightening you can be heightening they can be heightening
Perfect
I can have heightened you can have heightened he can have heightened we can have heightened you can have heightened they can have heightened
V-ing perfect
I can have been heightening you can have been heightening he can have been heightening we can have been heightening you can have been heightening they can have been heightening
Negation
Simple form
I can't heighten you can't heighten he can't heighten we can't heighten you can't heighten they can't heighten
V-ing form
I can't be heightening you can't be heightening he can't be heightening we can't be heightening you can't be heightening they can't be heightening
Perfect
I can't have heightened you can't have heightened he can't have heightened we can't have heightened you can't have heightened they can't have heightened
V-ing perfect
I can't have been heightening you can't have been heightening he can't have been heightening we can't have been heightening you can't have been heightening they can't have been heightening
Interrogative form
Simple form
can I heighten? can you heighten? can he heighten? can we heighten? can you heighten? can they heighten?
V-ing form
can I be heightening? can you be heightening? can he be heightening? can we be heightening? can you be heightening? can they be heightening?
Perfect
can I have heightened? can you have heightened? can he have heightened? can we have heightened? can you have heightened? can they have heightened?
V-ing perfect
can I have been heightening? can you have been heightening? can he have been heightening? can we have been heightening? can you have been heightening? can they have been heightening?
Interro-negative form
Simple form
can't I heighten? can't you heighten? can't he heighten? can't we heighten? can't you heighten? can't they heighten?
V-ing form
can't I be heightening? can't you be heightening? can't he be heightening? can't we be heightening? can't you be heightening? can't they be heightening?
Perfect
can't I have heightened? can't you have heightened? can't he have heightened? can't we have heightened? can't you have heightened? can't they have heightened?
V-ing perfect
can't I have been heightening? can't you have been heightening? can't he have been heightening? can't we have been heightening? can't you have been heightening? can't they have been heightening?