单选题 In order to prevent stress from being set up in the metal, expansion joints are fitted which ______ the stress by allowing the pipe to expand or contract freely.
【正确答案】 D
【答案解析】[解析] 句意：为了防止压力作用于金属上，安装了可扩充的接缝，它们通过允许管道自由扩张或缩小来减轻压力。relieve减少，减轻。reclaim回收，利用。reconcile使和解。rectify纠正，改正。