托福阅读里一个长难句的分析

In order for the structure to achieve the size and strength necessary to meet its propose, architecture employs methods of support that, because they are based on physical laws, have changed little since people first discovered them——even while building materials have changed dramatically.

这里的"because they are based on physical laws" 是一个插入语吗？

不是插入语，只不过是为了使句子更精彩而将原因状语放入句子中间，这样无形中就对不熟悉这种结构的同学造成了阅读障碍。其实我们自己在写作的时候，为了显得自己水平很高也会这样做，而且这种用法（原因状语，结果状语，时间状语等等插入到句子中间）在地道的英语文章中是很常见的。
这句话的正常语序是：In order for the structure to achieve the size and strength necessary to meet its purpose, architecture employs methods of support that have changed little since people first discovered them——even while building materials have changed dramatically，because they are based on physical laws.
一并帮你翻译一下：为了使建筑结构具有与其目的相适应的尺寸和力量，建筑师们采用了自从发现以来就几乎没怎么变化的支撑方法（尽管建筑材料已经发生了极大的改变），因为它们是基于物理规律的（言外之意是基于物理规律的东西是不可以轻易改动的）。
希望能帮到你，考试加油，我刚刚考过，有什么问题可以问我~~

能看懂,但是语法成分确实不太明白

widely reported, if somewhat distrusted, accounts by figures like the famous traveler from venice.marco polo, of the willingness of people in china to trade with europeans and of the immensity of the wealth to be gained by such contact made the idea irresistible。 subject : accounts working verb: made 句子主干是: accounts made the idea irresistible. 其他全是修饰语 widely reported 是opening clause， 修饰主语accounts,说这个accounts是 widely reported if somewhat distrusted 插入语，找主干意思时可以先暂时不看。 accounts by figures like the famous traveler from venice.marco polo （1） of the willingness of people in china to trade with europeans （2） and of the immensity of the wealth to be gained by such contact （3） 1.2.3都是修饰accounts的具体内容。找主干时也可以先忽略不看，直接奔向主谓宾，找到主干了，再看其他修饰语。

为了使结构在规模和强度上满足要求，建筑学采用了各种可行的方法，（因为它们都遵循了物理学原理），这些方法自从人们第一次发现它们起就基本没什么改变——即使是建筑材料有了显著的变化。 because they are based on physical laws 是插入语，对methods of support 起补充说明作用。 本句也可以改成： architecture employs methods of support that have changed little since people first discovered them，because they are based on physical laws