I must heighten you must heighten she must heighten we must heighten you must heighten they must heighten
V-ing form
I must be heightening you must be heightening she must be heightening we must be heightening you must be heightening they must be heightening
Perfect
I must have heightened you must have heightened she must have heightened we must have heightened you must have heightened they must have heightened
V-ing perfect
I must have been heightening you must have been heightening she must have been heightening we must have been heightening you must have been heightening they must have been heightening
Negation
Simple form
I must not heighten you must not heighten she must not heighten we must not heighten you must not heighten they must not heighten
V-ing form
I must not be heightening you must not be heightening she must not be heightening we must not be heightening you must not be heightening they must not be heightening
Perfect
I must not have heightened you must not have heightened she must not have heightened we must not have heightened you must not have heightened they must not have heightened
V-ing perfect
I must not have been heightening you must not have been heightening she must not have been heightening we must not have been heightening you must not have been heightening they must not have been heightening
Interrogative form
Simple form
must I heighten? must you heighten? must she heighten? must we heighten? must you heighten? must they heighten?
V-ing form
must I be heightening? must you be heightening? must she be heightening? must we be heightening? must you be heightening? must they be heightening?
Perfect
must I have heightened? must you have heightened? must she have heightened? must we have heightened? must you have heightened? must they have heightened?
V-ing perfect
must I have been heightening? must you have been heightening? must she have been heightening? must we have been heightening? must you have been heightening? must they have been heightening?
Interro-negative form
Simple form
must I not heighten? must you not heighten? must she not heighten? must we not heighten? must you not heighten? must they not heighten?
V-ing form
must I not be heightening? must you not be heightening? must she not be heightening? must we not be heightening? must you not be heightening? must they not be heightening?
Perfect
must I not have heightened? must you not have heightened? must she not have heightened? must we not have heightened? must you not have heightened? must they not have heightened?
V-ing perfect
must I not have been heightening? must you not have been heightening? must she not have been heightening? must we not have been heightening? must you not have been heightening? must they not have been heightening?