Among those taking TwHF extract, 12 left the study for these reasons.

在服用雷公藤的那些人中有12人因这些原因离开研究。

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But more research needs to be done before we know for certain that TwHF extract works and is safe.

不过，在我们确切地了解雷公藤提取物有效而且安全之前，还需要进行更多的研究。

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So we don't know how well TwHF extract works over the long term, and we don't know whether it's safe.

因此，我们不知道长期使用雷公藤所起的作用有多好，也不知道它是否安全。

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