metaphysics

她在大学里主修形而上学，研究存在的本质。

She majored in ___metaphysics at university, studying the fundamental nature of existence.

他的演讲陷入了形而上的讨论，对解决实际问题毫无帮助。

His speech wandered into ___metaphysics and offered no help for solving practical problems.

他喜欢研究形而上学，思考存在与意识的本质问题。

He enjoys studying ___metaphysics, contemplating the nature of existence and consciousness.