I must check you must check she must check we must check you must check they must check
V-ing form
I must be checking you must be checking she must be checking we must be checking you must be checking they must be checking
Perfect
I must have checked you must have checked she must have checked we must have checked you must have checked they must have checked
V-ing perfect
I must have been checking you must have been checking she must have been checking we must have been checking you must have been checking they must have been checking
Negation
Simple form
I must not check you must not check she must not check we must not check you must not check they must not check
V-ing form
I must not be checking you must not be checking she must not be checking we must not be checking you must not be checking they must not be checking
Perfect
I must not have checked you must not have checked she must not have checked we must not have checked you must not have checked they must not have checked
V-ing perfect
I must not have been checking you must not have been checking she must not have been checking we must not have been checking you must not have been checking they must not have been checking
Interrogative form
Simple form
must I check? must you check? must she check? must we check? must you check? must they check?
V-ing form
must I be checking? must you be checking? must she be checking? must we be checking? must you be checking? must they be checking?
Perfect
must I have checked? must you have checked? must she have checked? must we have checked? must you have checked? must they have checked?
V-ing perfect
must I have been checking? must you have been checking? must she have been checking? must we have been checking? must you have been checking? must they have been checking?
Interro-negative form
Simple form
must I not check? must you not check? must she not check? must we not check? must you not check? must they not check?
V-ing form
must I not be checking? must you not be checking? must she not be checking? must we not be checking? must you not be checking? must they not be checking?
Perfect
must I not have checked? must you not have checked? must she not have checked? must we not have checked? must you not have checked? must they not have checked?
V-ing perfect
must I not have been checking? must you not have been checking? must she not have been checking? must we not have been checking? must you not have been checking? must they not have been checking?