The sheer diversity of tropical plants represents a seemingly______source of raw materials , of which only a few have been utilized.

单项选择题Documenting science s______philosophy would be______, since it is almost axiomatic that many philosophers use scientific concepts as the foundations for their speculations.

单项选择题In the machinelike world of classical physics, the human intellect appears______, since the mechanical nature of classical physics does not______creative reasoning, the very ability that had made the formulation of classical principle possible.