名词
中文翻译：备用模块
同义词：
['supplementary module', 'spare unit']
例句：
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1.The engineer needs to replace the spare module in the machine.
工程师需要更换机器中的备用模块。
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2.The spare module is designed to be easily replaced when the main one fails.
备用模块设计为在主模块失效时容易更换。
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3. The spare module has been tested and found to be fully functional.
备用模块经过测试，发现完全功能正常。