求翻译：请同学们在10月15日下午三点，在学校礼堂举行讲座，讨论美国社会问题，我们主讲的是刚从美国访问回来的陈军老师，出席的是九年级全体同学，请大家准时到场是什么意思？

Students in the October 15, lecture in the school auditorium to discuss United States community issues, our keynote speaker is just from the United States access back June Chen teacher, was attended by all ninth grade students, please be on time