他对猫的恐惧毫无道理，猫其实很温顺。

His fear of cats is completely ___irrational, as they are actually very gentle.

科学家认为昆虫是没有理性思维能力的生物。

Scientists believe insects are ___irrational creatures incapable of reasoning.

圆周率是一个无限不循环的无理数。

Pi is an ___irrational number that never ends or repeats.