1. Rescuers used props to stop the roof of the tunnel collapsing. 救援人员用支柱防止隧道顶塌陷。
2. In architecture, a keystone in an archway or doorway is the stone that holds the whole thing together, and keeps it from collapsing. 建筑学中,拱道或门口的拱心石,是把建筑整体连接在一起来防止它倒塌的石头。
3. The building is in danger of collapsing. 这栋建筑有垮塌的危险。
4. He made it to the summit of Kilimanjaro before collapsing. 他成功登上乞力马扎罗山峰顶后倒下了。
5. The town's old quayside is collapsing after years of neglect. 这座小镇的旧码头区在多年疏于保养后快要坍塌了。