形容词
中文翻译：Unknown
同义词：
['ineffective', 'inefficient', 'unfruitful']
例句：
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1. The company's new product has been found to be unproductive.
公司的新产品被发现是无效的。
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2. The research was unproductive, as it did not lead to any significant findings.
这项研究是无效的，因为它没有带来任何重要的发现。
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3. The farmer's efforts were unproductive, as the yield was low.
农民的努力是无效的，因为产量很低。