obstruction marker

例句：

1. 1.The construction crew used a marker to mark the location of the new road.
   施工队使用标记物来标示新道路的位置。
2. 2. The police officer placed an obstruction marker in front of the entrance to prevent pedestrians from entering the restricted area.
   警察在入口处放置了一个障碍标志，以防止行人进入限制区域。
3. 3. The engineer marked the spot with a red marker before starting the excavation work.
   工程师在开始挖掘工作前用红色标记笔标出了地点。