nail-biting

例句：

1. 1.She was so bored that she started to nail-bite her fingernails.
   她非常无聊，开始咬指甲。
2. 2.He kept gnawing at his own thoughts until he finally gave up.
   他不断地啃自己的思想直到最后放弃。
3. 3. The child was constantly gnaw-gnawing at the end of his rope.
   这个孩子不断地啃他的绳子的末端。