scanning pencil of light

例句：

1. 1. The computer uses a scanning device to read the barcodes on the products.
   电脑使用扫描设备来读取产品上的条形码。
2. 2. The engineer used a scanning pencil of light to inspect the machine's components.
   工程师使用扫描光笔检查机器的部件。
3. 3. The police scanned the crowd for any suspicious activity.
   警方扫描人群以寻找任何可疑活动。