今日长难句：

选自《经济学人》

Indeed, there is a whole body of theory which suggests the very reason they manifest only in old age is because, in a state of nature, a human being would probably have died or been killed before they had had a chance to appear.

事实上，有许多理论表明，它们只有在晚年才表现出来，正是因为在自然状态下，一个人可能在有机会出现症状之前就已经死亡或被杀害了。

这个句子虽然不太长，但简直就是套娃中的极品，主句里套从句，然后从句里又套从句，然后从句里的从句又套从句。理解关键还是通过抓谓语动词，拆分出简单句，再说一遍英文中最重要的语法就是一个简单句中只能有一个谓语动词。

第一个简单句也是最大的框架是 there is a whole body of theory，谓语动词是be动词，there be句子整体气势是一个倒装结构，be后面的名词才是真正的主语，所以最外边的“套娃”意思就是说这有一整套理论；什么样的理论？第二个简单句就是which引导的定语从句修饰理论which suggests…体现出什么什么的理论，suggests是谓语动词；suggest后边又跟了一个宾语从句，也是第三个简单句，体现出什么了呢？the very reason is because….体现出了有一个原因是因为什么什么，is是谓语动词；第四个简单句是they manifest only in old age来修饰原因，它们只在晚年才体现出来的原因，manifest是谓语动词，它们指的什么需要看之前的句子。大家可以先暂停一下看一下下边的句子做一个指代题，本句话中的they指的是什么？They指的首先是前一句话中的them，传递到再前一句话，指的是Alzheimer阿尔茨海默症。

Moreover, illnesses like Alzheimer's are not exactly life-elongating. In the wild, any individual manifesting them would probably get short shrift from natural selection. Indeed, there is a whole body of theory which suggests the very reason / they manifest only in old age is because, in a state of nature, a human being would probably have died or been killed before they had had a chance to appear.

because 后边两个逗号中间的in a state of nature在自然状态下，属于插入语，跳过去，先不要管它，找到后边跟了第五个简单句 a human being would probably have died or been killed，一个人类也许会已经死亡或者已经被杀害了，注意这里是虚拟语气，所以需要用would而不是will，would have died or been killed是谓语动词；第6个简单句是before后边跟的they had had a chance to appear，谓语动词是had。

把这些句子的意思拼在一起看，这句话的意思我掰碎了给大家翻译一下，

简单句1: 事实上，这里有一整套理论

简单句2: 这个理论显示出来一个东西

简单句3:（显示出来一个）原因是因为什么什么

简单句4:（什么样的原因？）它们只在晚年显现出来（的原因）

简单句5:（原因是）一个人可能会已经死亡或被杀害了

简单句6:（什么时候死亡或者被杀害）它们有机会出现症状（之前）

所以，这句话整体的意思就是：事实上，有许多理论表明，它们只有在晚年才表现出来的原因是因为，在自然状态下，一个人可能在有机会出现症状之前就已经死亡或被杀害了。

核心要点：

1.a whole body of 一整个

例：This very important work created the impression of English law as a whole body of connected principles.

这部相当重要的作品给世人以英格兰法是一个有机联系的原则所组成的完整实体的初步印象。

2.in a state of nature 处于原始状态/自然状态

例：But the juicy steak, the nourishing wheat grain, the loyal dog and the affectionate cat never existed in a state of nature.

可是，自然界从来不曾存在鲜美多汁的牛排、营养丰富的麦粒、忠实的宠物狗、以及柔情万种的宠物猫。

3.manifest v. 表明，清楚显示（尤指情感、态度或品质）[近义词：demonstrate]

例：Social tensions were manifested in the recent political crisis.

最近的政治危机显示了社会关系的紧张。

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