roll opening indicator

例句：

1. 1. The roll-up indicator shows that the temperature has risen by 5 degrees Celsius.
   卷轴开口指示器显示温度上升了5摄氏度。
2. 2. The roll-up indicator is used to indicate when a vehicle is about to stop.
   卷轴开口指示器用于指示车辆即将停止。
3. 3. The roll-up indicator can be seen on the front of the car, indicating that it is ready foruse.
   卷轴开口指示器位于汽车前部，表示汽车已准备好使用。