The army has not yet proffered an explanation of how and why the accident happened.

军队还没有提供对该事故如何发生以及为什么发生的解释。

《柯林斯英汉双解大词典》

To argue for a cause-and-effect relationship, scientists must attempt to explain why and how a connection could occur.

想要证明因果关系，科学家们必须尽量解释这种联系可能出现的原因和方式。

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Why and how can it take place?

这件事为什么会发生，它又是如何发生的呢？

youdao

Plate tectonics is the area of science that explains why the surface of the Earth changes and how those changes cause earthquakes.

VOA: special.2010.01.12

That's why many of them are thinking really very hard of how to foster entrepreneurship, how to encourage innovation.

这就是为什么大家都在思索,如何才能培养企业家精神，如何鼓励创新。

斯坦福公开课 - 百度CEO李彦宏演讲：全球最大搜索引擎的发展课程节选

It has traditional stories and legends, some quite fanciful, Whose goal it is to explain how and why something is what it is.

它讲述了一些传统故事，有一些还极具想象力，它们试图解释事物的形成方式及成因。

耶鲁公开课 - 旧约导论课程节选

Other research has sought to measure exactly how employees react to punishment and reward, why people seem to value money they've earned over money they're given, and why and how people lie.

FORBES: Magazine Article

What companies could reap the greatest rewards by starting such a program, why and how?

FORBES: Make Your Company Top-of-Mind and Your Employees Proud

To see why and how, start with an overview of China's current growth model.

WSJ: China's Consumption Conundrum