指示者

例句：

1. 1.The traffic light is an excellent indicator ofthe road conditions.
   交通灯是道路状况的绝佳指示。
2. 2. The new product isa clear indicator of its quality.
   新产品是其质量的明显指示。
3. 3. Thepresence of the hawkis an unmistakable indicator of danger.
   鹰的出现无疑是危险的标志。