key brick

例句：

1. 1.The construction of the bridge required the use of key bricks for its foundation.
   建造桥梁需要使用关键的砖块来作为其基础。
2. 2.The engineer used key bricks to reinforce the structure's stability.
   工程师使用了关键的砖块来加固结构的稳定性。
3. 3.The restoration project involved the replacement of key bricks in the old building.
   修复项目包括在旧建筑中更换关键的砖块。