He had a profound knowledge of mantras and their efficacy.

他深谙各种咒语及其功用。

youdao

But there are still many questions about both their safety and their efficacy.

但人们对它的安全性和功效仍然有很多疑问。

youdao

But there are still many questions about both their safety and their efficacy.

但人们对它的安全性和功效仍然有很多疑问。

youdao