55.There is supposed to be a safety ___________ which makes it impossible for trains to collide.
A.appliance 机械 装置
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 恶化 变化=degenerate 变坏 堕落
B.dispersed 散开 消散
C.dissipated 消散 消失
D.drained 耗尽
解析：
finally 最终
dominish 消失减少 (同义：smother eliminate)
shrink 缩水
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