The unutilized balance of $3,553,400 under this heading was primarily attributable to lower requirements for the installation of six bailey bridges and lower costs for the repair of bridges in the mission area.
18. 本项目下产生3 553 400美元未用余额的主要原因是六座贝雷桥的安装费以及任务区桥梁维修费均有下降。