I must tough you must tough he must tough we must tough you must tough they must tough
V-ing form
I must be toughing you must be toughing he must be toughing we must be toughing you must be toughing they must be toughing
Perfect
I must have toughed you must have toughed he must have toughed we must have toughed you must have toughed they must have toughed
V-ing perfect
I must have been toughing you must have been toughing he must have been toughing we must have been toughing you must have been toughing they must have been toughing
Negation
Simple form
I must not tough you must not tough he must not tough we must not tough you must not tough they must not tough
V-ing form
I must not be toughing you must not be toughing he must not be toughing we must not be toughing you must not be toughing they must not be toughing
Perfect
I must not have toughed you must not have toughed he must not have toughed we must not have toughed you must not have toughed they must not have toughed
V-ing perfect
I must not have been toughing you must not have been toughing he must not have been toughing we must not have been toughing you must not have been toughing they must not have been toughing
Interrogative form
Simple form
must I tough? must you tough? must he tough? must we tough? must you tough? must they tough?
V-ing form
must I be toughing? must you be toughing? must he be toughing? must we be toughing? must you be toughing? must they be toughing?
Perfect
must I have toughed? must you have toughed? must he have toughed? must we have toughed? must you have toughed? must they have toughed?
V-ing perfect
must I have been toughing? must you have been toughing? must he have been toughing? must we have been toughing? must you have been toughing? must they have been toughing?
Interro-negative form
Simple form
must I not tough? must you not tough? must he not tough? must we not tough? must you not tough? must they not tough?
V-ing form
must I not be toughing? must you not be toughing? must he not be toughing? must we not be toughing? must you not be toughing? must they not be toughing?
Perfect
must I not have toughed? must you not have toughed? must he not have toughed? must we not have toughed? must you not have toughed? must they not have toughed?
V-ing perfect
must I not have been toughing? must you not have been toughing? must he not have been toughing? must we not have been toughing? must you not have been toughing? must they not have been toughing?