我是说，为什么需要动机，为啥杀人需要理由？

I mean, who needs motif, who needs a reason to kill.

youdao

医生和牙医有着很明显的过度治疗病人的动机，举个例子，这解释了为什么在美国估计有75%的智齿原本是不需要拔掉的。

There’s an obvious financial motivation for doctors and dentists to overtreat people, which explains why, for instance, 75% of wisdom tooth extractions in the US are estimated to be unnecessary.

youdao

虽然德国汽车制造商很清楚需要开为什么样的新技术(更小的发动机，更高效的自动变速箱，多种类的混合动力和生物燃料的更佳利用)，得他们还是力争不已。

Even though it is clear what new technologies will be needed (smaller engines, more efficient automatic transmissions, various kinds of hybrid and greater use of biofuels) the Germans will struggle.

youdao

它实际上需要不到一整天更使每个发动机，这就是为什么我只作小批量，只有在时间允许的。

It actually takes more than a full day to make each engine, which is why I only make small batches and only when time allows.

youdao

医生和牙医有着很明显的过度治疗病人的动机，举个例子，这解释了为什么在美国估计有75%的智齿原本是不需要拔掉的。

There's an obvious financial motivation for doctors and dentists to overtreat people, which explains why, for instance, 75% of wisdom tooth extractions in the US are estimated to be unnecessary.

youdao

医生和牙医有着很明显的过度治疗病人的动机，举个例子，这解释了为什么在美国估计有75%的智齿原本是不需要拔掉的。

There's an obvious financial motivation for doctors and dentists to overtreat people, which explains why, for instance, 75% of wisdom tooth extractions in the US are estimated to be unnecessary.

youdao