Researchers now postulate that addiction requires two things .

研究者假定成瘾需要两个基本条件。

It seems that they would look for any explanation rather than postulate a new particle .

他们似乎更愿意寻找任何可能的解释也不愿去假定存在这种新粒子。

First , we must postulate that if souls exist , they must have some mass .

第一，我们必须假定灵魂存在，他们必须保有物质。

But the postulate worked only as long as it was applied to the exchange of physical goods .

但是这个假定只在应用于实物交换时才成立。

I think we can postulate a utility function along the following lines : having a christmas tree up during the christmas season brings positive utility , but diminishing marginal utility over time .

我觉得我们可以按照以下思路来假定一个效用函数：在圣诞节期间有一棵圣诞树可以带来正的效用，但随着时间流逝，边际效用就会递减。