求翻译：这是上午上课时，老师和全班同学互相问候时用语。Good morning 是上午问候时的用语，多用于熟人，朋友或家人之间，是比较正式的问候用语。句中问候语放在前面，称呼语则要放在后面，并用逗号隔开。例如：是什么意思？

This is morning in class, the teacher and the class when greeting each other term. Good morning is morning greetings of terms, used for acquaintance, between friends or family, is a more formal greeting phrases. Sentence of greeting at the front, salutations are in the back, and separated by commas.