卷缩

例句：

1. 1. The fabric has started to sag at the edges.
   布料的边缘开始下垂。
2. 2. The balloon popped when it hit the ground.
   气球落地时爆了。
3. 3. The roots of the tree are starting to sink into the soil.
   树根开始向土壤里陷。