The search for a wonder drug to cure obesity clearly wasn't at an end.对治疗肥胖的神奇药物所进行的探索，无疑并没有就此结束

at an end:结束

Our hunt for a house is at last at an end.

我们找房子的事情终于有了结果。

They wished the voyage at an end.

他们渴望航行结束。

They didn't examine fat people,but concentrated on thin ones instead.他们没有去调查肥胖人群而是把注意力集中在瘦人身上

concentrate on:集中于； 专心于

It's too hot to concentrate on book.

热得不能集中心思看书。

I can't concentrate on my work when I'm tired.

我累了就无法集中精力工作。

concentrate，focus这两个动词均有“集中，聚集”之意。

concentrate指把人或物集中在一起，也可指把精力或注意力集中于某一事物上。

focus侧重指把光、热、射线等集中于一点，也可指把思想或精力等集中于某人或某事情上。

And in order to study that,he needed to take a group of people and make them fat. 为了进行这项研究他需要选择一组人并把他们变胖

in order to:为了

We started early in order to arrive before dark.

为了在天黑前到达，我们很早就动身了。

We learn a language in order to communicate.

我们学习语言是为了交流思想。

a group of:一组； 一群； 一伙

We came up with a group of tourists.

我们赶上了一群旅游者。