传说中，刻耳柏洛斯是一只有三个头的恶犬，守护着冥界的入口。

In the myth, ___Cerberus is a three-headed dog that guards the gates of the underworld.

图书馆管理员就像刻耳柏洛斯一样，严格检查每个人的借书证。

The librarian was like ___Cerberus, strictly checking everyone's library card.