1. 宣布：29.Go back to your seat, please. 回到座位上. | 1.2.3. Announcing宣布 | 30.Let's start now./Let's begin our class/lesson.让我们开始上课吧.

2. 布告：announciator 报警器 | announcing 布告 | annual aberration 周年光行差

3. 公布：announciator 通告者 | announcing 公布 | annoy 使苦恼