Experiments have also cast serious doubt on the belief that yawning is triggered by a drop in blood oxygen or a rise in blood carbon dioxide.

对于打哈欠是由血液中的氧气减少或血液中的二氧化碳增加引起的这种观点，一些实验也同样提出了严重的质疑。

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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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A circular blood drop could mean the blood fell directly downward.

VOA: special.2010.05.05

Being so caught up, So mastered by the brute blood of the air, Did she put on his knowledge with his power Before the indifferent beak could let her drop?

就这样被征服，这样被天空中野性的血液欺凌，她是否借他之力获得了知识,在那一意孤行的嘴放她下来之前？

耶鲁公开课 - 现代诗歌课程节选

The result is a five to twenty percent drop in the amount of oxygen in the blood.

VOA: special.2009.07.14

Two patients with especially advanced ALL experienced what Dr. Brentjens termed a "shake and bake response" significant fever and a drop in blood pressure that resulted in their admission to intensive care.

WSJ: Gene Therapy Shows Promise as Cancer Treatment