And although using a metabolic ward is great in terms of testing accuracy, we obviously don't live in huge gas-measuring boxes so the researchers also performed a 15-day free living trial.

尽管使用代谢室在测试准确性方面有很可靠的结果，但我们显然不是住在巨大的气体测量箱里，所以研究人员还进行了为期 15 天的自由生活试验。

In the first half of the 1800s, most of these slaves were in the southern part of the U.S., but many of the blacks who had originally been slaves were free, living in the northern U.S. states.

1800年代上半叶，这些奴隶大多在美国南部， 但许多原本为奴的黑人获得了自由，居住在美国北部各州。