55.There is supposed to be a safety ___________ which makes it impossible for trains to collide.

　　A.appliance 機(jī)械 裝置

　　B.accessory 附件 零件 配件

　　C.machine

　　D.mechanism

　　56.After four years in the same job his enthusiasm finally _______ .

　　A.deteriorated 惡化 變化=degenerate 變壞 墮落

　　B.dispersed 散開(kāi) 消散

　　C.dissipated 消散 消失

　　D.drained 耗盡

　　解析：

　　finally 最終

　　dominish 消失減少 (同義：smother eliminate)

　　shrink 縮水