focus plate

例句：

1. 1. The teacher placed a focus plate on the blackboard to help students concentrate.
   老师在黑板上放了一块聚焦板来帮助学生集中注意力。
2. 2.During the presentation, the speaker used a focus plate to emphasize important points.
   演讲者在演讲时使用了一块聚焦板来强调重点。
3. 3.The engineer designed a focus plate that could be easily adjusted for different tasks.
   工程师设计了一块可调整的聚焦板，以适应不同的任务需求。