城堡城墙上的锯齿状垛口既美观又具有防御功能。

The castle's ___crenellations served both for protection and as a decorative feature.

这座花园围墙上的锯齿状装饰只是为了美观，并非真正的防御工事。

The ___crenellation on the garden wall is purely decorative, not meant for actual defense.