装满书的架子开始往下弯了。

The shelf ___is sagging under the weight of the books.

由于缺乏新客户，我们的销售额最近一直在下滑。

Our sales have been ___sagging recently due to a lack of new customers.

旧窗帘因为年久失修而松垮地垂着。

The old curtains were ___sagging loosely due to years of wear.