zone of silence marker

例句：

1. 1. The researchersused a laser to create a zone ofsilence in the lab.
   研究人员使用激光在实验室中创造了一个沉默区。
2. 2. The scientists markedthe boundary between the two zones witha red dot.
   科学家们用红点标记了两个区域的边界。
3. 3. The silencemarker was placed at theentrance to the restricted area.
   沉默区标记被放置在限制区域入口处。