英语翻译边际效用递减规律物以稀为贵,当消费者偏好某物而未能获得,或拥有数量不够大时,增加消费量则其满足感大增（边际效用增

边际效用递减规律
The law of diminishing marginal utility

物以稀为贵, 当消费者偏好某物而未能获得,或拥有数量不够大时,增加消费量则其满足感大增（边际效用增加）；但拥有数量足够时,再增加消费量则其满足感增加幅度逐渐平缓（边际效用递减）；
Whena thing is rare, it becomes precious. When consumers cannot get the things that they prefer or their possessed quantities were less than what they wanted, increasing of their consumption will increase their satisfactions (increase of marginal utility). But when the possessed quantities are enough, increasing of their consumptions would increase their satisfaction gradually and slowly(diminishing marginal utility).

拥有数量太多时,再增加消费量则反而感觉厌恶.比如说我有几天没有吃饭了,突然有了饭吃.第一碗我很快就吃完了,然后还想吃第二碗.
When the possessed quantities are too great, any increase in consumption will only lead to negative results and might feeling disgusted. Just like when I haven't been eaten for several days. Then suddenly there is something to eat. The first bowl I ate would be most satisfying, but I would not like to eat the second bowl. (下面一段似乎有点重复,但我还是照样替你翻译了,你自己可以随意更正.)

比如说我有几天没有吃饭了,突然有了饭吃.第一碗我很快就吃完了,然后还想吃第二碗.马上第二碗也快速的吃完了,这时候我感觉有点饱了不怎么想吃了.这时候给我上了第三碗,这时候我就不会去吃了,应为我已经吃饱了就不会想吃了.
Such as I haven't been eaten for many days, suddenly there is something to eat. I will the first bowl very quickly, then eat the second and I will also eat that quickly too. By then I would feel a bit full and might not want to eat anymore. If a third bowl is given to me and I would not eat it. I think that I am already full so I don't want eat it any more.

而在经济学中第一碗饭给我的效用是最大的,第二碗饭虽然也吃完了但是不想第一碗带来的效用那么高.而到第三碗时我已经饱了不想吃了,再吃的话,饭给我的效用是负的.不仅没能给我好处,反而是负担让我感到厌恶.
In the economy, the utility that the first bowl gave was the greatest. Although I have also finish the second bowl as well, its utility was not as high as the first bowl and because I was allready full up so didn't feel like to eat the third bowl. If I had carried on eating, the utility I got would negative. It would not just couldn't do me any good but instead, It may make me feeling sick.

今天就这麼多了,任务全部已完成,谢谢你的求助,希望对你真的会有所帮助.

Diminishing (marginal) return,
Goods are of higher value when its scarce. If a consumer prefer a good but did not have enough of it, increasing his demand will increase his satisfaction, which is ...