I must look you must look she must look we must look you must look they must look
V-ing form
I must be looking you must be looking she must be looking we must be looking you must be looking they must be looking
Perfect
I must have looked you must have looked she must have looked we must have looked you must have looked they must have looked
V-ing perfect
I must have been looking you must have been looking she must have been looking we must have been looking you must have been looking they must have been looking
Negation
Simple form
I must not look you must not look she must not look we must not look you must not look they must not look
V-ing form
I must not be looking you must not be looking she must not be looking we must not be looking you must not be looking they must not be looking
Perfect
I must not have looked you must not have looked she must not have looked we must not have looked you must not have looked they must not have looked
V-ing perfect
I must not have been looking you must not have been looking she must not have been looking we must not have been looking you must not have been looking they must not have been looking
Interrogative form
Simple form
must I look? must you look? must she look? must we look? must you look? must they look?
V-ing form
must I be looking? must you be looking? must she be looking? must we be looking? must you be looking? must they be looking?
Perfect
must I have looked? must you have looked? must she have looked? must we have looked? must you have looked? must they have looked?
V-ing perfect
must I have been looking? must you have been looking? must she have been looking? must we have been looking? must you have been looking? must they have been looking?
Interro-negative form
Simple form
must I not look? must you not look? must she not look? must we not look? must you not look? must they not look?
V-ing form
must I not be looking? must you not be looking? must she not be looking? must we not be looking? must you not be looking? must they not be looking?
Perfect
must I not have looked? must you not have looked? must she not have looked? must we not have looked? must you not have looked? must they not have looked?
V-ing perfect
must I not have been looking? must you not have been looking? must she not have been looking? must we not have been looking? must you not have been looking? must they not have been looking?