To do reliable research on any condition, scientists must agree on the specific characteristics that make up that condition so they're all talking about the same thing, and with PMS, this has not been the case.
无论在任何条件下，可靠的研究 都要求科学家必须就构成这种条件的 特征达成一致， 这样才能确保讨论的是同一个概念， 但对于经前综合征来说，情况并非如此。