由于地基不稳，那座桥有坍塌的危险。

The bridge is at risk of ___collapsing due to its unstable foundation.

由于多年的管理不善，这家公司正在彻底崩溃。

After years of poor management, the company is ___collapsing completely.

老人家在烈日下站得太久，突然晕倒了。

The old man stood in the scorching sun for too long and suddenly ___collapsed.