名词
中文翻译：Unknown
同义词：
['backup', 'spare', 'backup unit例句：1. We need to have a backup plan in case of emergencies.（我们需要一个应急计划。）2. The company has a spare machine for when the main one breaks down.（公司有一台备用机器，当主要的机器坏了时可以用。）3. The backup system is designed to provide an alternative power source in case of a power outage.（备用系统设计为在电力中断时提供替代电源。）']
例句：
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1. We need to have a backup plan in case of emergencies.
我们需要一个应急计划。
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2. The company has a spare machine for when the main one breaks down.
公司有一台备用机器，当主要的机器坏了时可以用。
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3. The backup system is designed to provide an alternative power source in case of a power outage.
备用系统设计为在电力中断时提供替代电源。