classes:  lecturer. there will be a specific attendance announcement on the machine room to fix the exercise for those who do not understand how to do.  curriculum. there will be a specific attendance announcement on the machine room to fix the exercise for those who do not understand how to do.  facility. there will be a specific attendance announcement on the machine room to fix the exercise for those who do not understand how to do.  general. there will be a specific attendance announcement on the machine room to fix the exercise for those who do not understand how to do.