I must group you must group he must group we must group you must group they must group
V-ing form
I must be grouping you must be grouping he must be grouping we must be grouping you must be grouping they must be grouping
Perfect
I must have grouped you must have grouped he must have grouped we must have grouped you must have grouped they must have grouped
V-ing perfect
I must have been grouping you must have been grouping he must have been grouping we must have been grouping you must have been grouping they must have been grouping
Negation
Simple form
I must not group you must not group he must not group we must not group you must not group they must not group
V-ing form
I must not be grouping you must not be grouping he must not be grouping we must not be grouping you must not be grouping they must not be grouping
Perfect
I must not have grouped you must not have grouped he must not have grouped we must not have grouped you must not have grouped they must not have grouped
V-ing perfect
I must not have been grouping you must not have been grouping he must not have been grouping we must not have been grouping you must not have been grouping they must not have been grouping
Interrogative form
Simple form
must I group? must you group? must he group? must we group? must you group? must they group?
V-ing form
must I be grouping? must you be grouping? must he be grouping? must we be grouping? must you be grouping? must they be grouping?
Perfect
must I have grouped? must you have grouped? must he have grouped? must we have grouped? must you have grouped? must they have grouped?
V-ing perfect
must I have been grouping? must you have been grouping? must he have been grouping? must we have been grouping? must you have been grouping? must they have been grouping?
Interro-negative form
Simple form
must I not group? must you not group? must he not group? must we not group? must you not group? must they not group?
V-ing form
must I not be grouping? must you not be grouping? must he not be grouping? must we not be grouping? must you not be grouping? must they not be grouping?
Perfect
must I not have grouped? must you not have grouped? must he not have grouped? must we not have grouped? must you not have grouped? must they not have grouped?
V-ing perfect
must I not have been grouping? must you not have been grouping? must he not have been grouping? must we not have been grouping? must you not have been grouping? must they not have been grouping?