The specimen, complete with surrounding rock, had been on display for the past 50 years at a museum in Poland, but amazingly no one had spotted the footprint.

这个标本连同周围的岩石，在过去的50年里一直在波兰的一家博物馆陈列，但令人惊讶的是，从未有人发现这个脚印。

If the volcano becomes inactive and cools, surrounding rock may be worn away.

如果火山变得不活动并冷却下来，围岩就可能被剥蚀掉。

Underground structures, being confined by the surrounding rock or soil, have long been assumed to have good anti-seismic ability.

地下结构由于受到周围岩体或土体的约束，一直被认为具有良好的抗震性能。