This is because a copying collector does not need to visit or copy dead objects, only live ones.

这是因为，拷贝收集器不需要访问或拷贝死对象，只处理活动对象。

youdao

The Send button gets pushed only three times, yet seven copies of the same message appear in differing states for three people—each copy a dead version of another.

发送按钮仅仅被按了三次，然而却有7个相同的邮件副本以不同的状态在三个人的邮箱中出现——每个副本对另外一个副本来说都是一个无法修改的拷贝。

youdao

On my first day as a copy editor I opened mine to be greeted by a dead rat.

FORBES: Connect

But if you want to sell back Red Dead Redemption, Mass Effect 3 and Skyrim to help you pay for half the cost of a physical copy of the game on launch day, I suppose you have that right.

FORBES: Dreaming of a Day When All Games Are Released Digitally Like Diablo 3