Regarding the experiment animals, encaged mountain hares caught from wild field were used.

实验用的动物，选择了从野外捕捉不久的雪兔个体。

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This experiment was harmless to the animals.

这个实验对动物无害。

《柯林斯英汉双解大词典》

This 700-million-year-old formation gives few clues to the origins of modern animals, however, because paleontologists believe it represents an evolutionary experiment that failed.

然而，这个7亿年历史的地层几乎不能为现代动物的起源提供任何线索，因为古生物学家认为它代表的是一个失败的进化试验。

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This first experiment, however, had engaged only the animals' spinal cords.

ECONOMIST: An experiment on rats brings hope to the paralysed

It almost felt like a sociological experiment designed to prove the obvious: that readers are herd animals, that heat begets heat.

NEWYORKER: Search and Destroy

The directive - which replaces laws in place since 1986 - would prevent experiments using animals from going ahead without prior authorisation, including an assessment of the ethical implications of the experiment.

BBC: Animal welfare laws