他的研究遵循实证主义原则，只接受可验证的实验结果。

His research follows the principles of ___positivism, accepting only verifiable experimental results.

即使在疫情最严重的时候，他的乐观精神也感染了周围的人。

During the toughest time of the pandemic, his ___positive attitude lifted the spirits of those around him.