approximity warning indicator

例句：

1. 1. The two buildings are approximately50 meters apart.
   这两栋楼相距大约50米。
2. 2. The similaritybetween the two cultures isremarkable.
   这两种文化之间的相似性令人印象深刻。
3. 3. The proximity of the two citiesmakes it easy to travel between them.
   这两个城市的接近使得它们之间的旅行变得容易。