sag

The old bookshelf began to sag under the weight of hundreds of heavy encyclopedias.

(Chinese) 旧书架在数百本厚重百科全书的重压下开始向下弯曲。

After the ten-mile hike, his shoulders started to sag with exhaustion.

(Chinese) 徒步十英里后，他的双肩因精疲力竭而垂了下来。