hollow foot

例句：

1. 1.The tree is hollow, so it can't support the weight of a person.
   这棵树是空心的，所以它不能支撑一个人的重量。
2. 2. The hollow sound echoed through the cave.
   空洞的声音在洞穴中回荡。
3. 3.The hollow feeling in my stomach made me feel uneasy.
   肚子里的空虚感让我感到不安。