What's the university's absenteeism rate?
It is advisable to find out in advance for each course how many absences you are allowed. There is a difference in whether the absences are unexcused or excused. A student has the right to a minimum of one unexcused absence per semester from compulsory teaching activities in a given course; this does not apply to intensive courses or specially scheduled courses (see Article 9, paragraph 2 of the MU Study and Examination Regulations). The teacher may set a higher tolerance for absences.
Beware of classes with special timetables, where absences may not be allowed at all.