In lab tests using blood samples from human volunteers, the scientists showed that a drop of blood placed on the strip caused a color change that indicated blood type.
研究人员从志愿者身上采集血液样本用于试验，将血液滴在试纸上，根据试纸颜色的变化来区分血型。
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Scientists still have a lot of work to do before the color-changing molecules can be used outside the lab.
在这种变色分子走出实验室投入应用之前，科学家们仍有大量工作要做。
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In a park in Paris city centre, pigeons were fed by two researchers, of similar build and skin color, wearing different colored lab coats.