书架上的那些旧书是最积灰的。

The old books on the shelf are the ___dustiest.

我擦了一下书架，结果手指变得满是灰尘。

After wiping the shelf, my fingers became the ___dustiest part of my hand.

我们在阁楼里发现了那些积满灰尘的玩具，它们已经被遗忘多年了。

We found those ___dustiest toys in the attic, forgotten for years.