Obstacles
n. 障碍（物）( obstacle的复数形式 ); 障碍物; 绊脚石; 障碍栅栏
🗣️ 情景例句
You can do it.
可以这样做。
What is happening down there?
下面发生什么事情？
and so the tools of long ago have remained when even the bones of the men who made them have disappeared without trace.
因此，尽管制造这些工具的人的骨头早已荡然无存，但远古时代的石头工具却保存了下来。