reference cycle relatives

例句：

1. 1. The book is a valuable reference for anyone studying history.
   这本书是任何研究历史的人宝贵的参考资料。
2. 2. He cited the example to support his argument.
   他引用这个例子来支持他的论点。
3. 3. She referred to her notes when explaining the concept.
   当她解释这个概念时，她提到了她的笔记。