however primitive
然而原始
以上为机器翻译结果，长、整句建议使用 人工翻译 。
The loss of the springs brought with it a loss of the natural filtration of soil and sand, however, so the Maya built their own primitive filtration systems, forcing their rainwater runoff through boxes of sand, the researchers found.
MSN: Sustainable tech saw the ancient Maya through drought
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