在开班会时，老师可以说:

"Good morning/afternoon/evening, everyone. Welcome to the new school year/semester." (早上/下午/晚上好，大家好。欢迎来到新的学年/学期。)
"I hope you all had a great summer/vacation and are ready to get back to work." (我希望你们都度过了愉快的暑假/假期，并且准备好回去上课了。)
"Before we get started, let's go around the room and introduce ourselves. My name is [Name], and I will be your [teacher/professor] for [subject/class]." (在我们开始之前，让我们在教室里绕一圈并自我介绍一下。我的名字是[名字]，我将是你们的[老师/教授]，教授[科目/班级]。)
"I'm looking forward to working with all of you this year/semester and helping you achieve your academic goals." (我期待着在今年/学期与大家一起工作，并帮助你们实现学业目标。)

这些表达都是常见的开班会用语，常用于学校或大学的开学典礼或班会中。