What is the main topic of this conversation?

这段对话的主题是什么？

同一单元的其他句子

• The lecture hall was crowded with students taking notes.演讲厅里挤满了做笔记的学生。
• Could you please repeat the last part of the announcement?你能重复一下公告的最后部分吗？
• She missed the bus, so she arrived late for the seminar.她错过了公交车，所以研讨会迟到了。
• The professor's accent was difficult to understand at first.教授的口音起初很难听懂。
• We need to submit the assignment by Friday noon.我们必须在周五中午前提交作业。