请教这篇GWD阅读，没看懂，能否解释下答案

GWD 26-Q7 to Q9

There is no consensus among researchers regarding what qualifies a substance as a pheromone. While most agree on a basic definition of pheromones as chemicals released by one individual of a species which, when detected by another individual of the same species, elicit a specific behavioral or physiological response, some researchers also specify (10) that the response to pheromones must be unconscious. In addition, the distinction between pheromones and odorants— chemicals that are consciously detected as odors---can be blurry, and some researchers classify pheromones as a type of odorant. Evidence that pheromone responses may not involve conscious odor perception comes from the finding that in many species, pheromones are processed by the vomeronasal (or accessory olfactory) system, which uses a special structure in the nose, the vomeronasal organ (VNO), to receive chemical signals. The neural connections between the VNO and the brain are separate from those of the main olfactory system, whose processing of odorants triggers sensations of smell. But while the VNO does process many animal pheromone signals, not all animal pheromones work through the VNO. Conversely, not all chemical signals transmitted via the VNO quality as pheromones. For example, garter snakes detect a chemical signal from earthworms—one of their favorite foods—via the VNO, and they use this signal to track their prey.

It can be inferred from the passage that in classifying pheromones as a type of odorant, the researchers referred to in line 15 posit that

A.         pheromones are perceived
            consciously

B.         most pheromones are processed
            by the VNO

C.         most chemical signals processed
            by the VNO are pheromones

D.         pheromone perception does not
            occur exclusively between members of the same species.

E.         pheromones do not always elicit
            a specific behavioral or physiological response

--------------------------------------------------------------------Q8

According to the passage, the fact that
            pheromones are processed by the VNO in many animal species has been taken
            as evidence of which of the following?

A.      The accessory and main olfacstory systems are not separate

B.       Odorants and pheromones are
            not distinct types of chemicals.

C.      Odorants and pheromones both
            elicit a specific behavioral
            response.

D.      Pheromones do not trigger conscious sensations of smell.

E.       Pheromones aid animals in tracking prey.

------------------------------------------------------------------

Q9: The primary purpose of the passage is to

A.      compare and contrast the ways
            in which the vomeronasal organ
            and the main olfactory systern
            process chemicals.

B.       summarize the debate over the
            role the vomeronasal organ plays in odor perception

C.      present some of the issues
            involved in the debate over
            what constitutes a pheromone

D.      propose a new definition of
            pheromones based on recent
            research

E.       argue that pheromones should be
            classified as a type of odorant

答案为ADE；谢谢！

Q7问题是：”可以从文章中推断出，将通过（in）pheromones归类成odorant，第15行中提到的researchers断定（posit）...“

所以问题是关于pheromones和odorant的联系的。从文章中可以得出，两者之间的区别是pheromones会引起”unconscious“的response，而odorants会引起”consciously“的response。所以将pheromones归类成odorant，就是说pheromones也会引起consciously的反应。

再看选项：

B.         most pheromones are processed
        by the VNO - 提到
        consciously和VNO的关系，而文章提到，VNO和olfactory system不同，olfactory system ”whose processing of odorants triggers sensations of smell“，也就是能产生conscious的反应，则VNO就无法产生conscious的反应。无关项。

C.         most chemical signals processed
        by the VNO are pheromones - 同B，说了pheromones和VNO的关系，没有提到 pheromones和odorants的关系。无关项。

D.         pheromone perception does not
        occur exclusively between members of the same species. - 这是对pheromone的另一个特性的说明，和odorant无关。

E.         pheromones do not always elicit
        a specific behavioral or physiological response. - 这个也是对pheromone的特性的说明，虽然也没错，但是无关。

所以正确答案就是A。

问题是” 根据原文，在很多动物物种中，
        pheromones 是由VNO来process的，这个事实被用来作为证据证明下面的哪个选项？“

所以是supporting fact类型的题目，原文中会由很明确的地方提出所需答案。

返回原文定位，相关句子是”Evidence
that pheromone responses may not involve conscious odor perception
comes from the finding that in many species, pheromones are processed
by the vomeronasal (or accessory olfactory) system, which uses a
special structure in the nose, the vomeronasal organ (VNO), to receive
chemical signals. “

所以可以看到，文章说pheromones are processed
by the vomeronasa的目的，是为了说明前面的"pheromone responses may not involve conscious odor perception“，即pheromone 不一定会引起气温上的conscious的反应。

再看问题。可以看到选项D正好是这个意思。所以选D。

A.      The accessory and main olfacstory systems are not separate

B.       Odorants and pheromones are
        not distinct types of chemicals.

C.      Odorants and pheromones both
        elicit a specific behavioral
        response.

D.      Pheromones do not trigger conscious sensations of smell.

E.       Pheromones aid animals in tracking prey.

Q9:

问题是”文章写作的目的是为了...“。

主旨题。我的做法是先总体回顾一下原文的大概结构和目的，然后一个个看答案选项。原文第一句”There is no consensus among researchers regarding what qualifies a substance as a pheromone.“应该是中心句。所以文章主要是说对于pheromone的分类大家一直有分歧”，后面的正文也是举了几个例子，说明pheromone和odorants之间容易混淆，以及通过VNO来分类也会造成分歧，等等。

然后一个个看选项：

A.      compare and contrast the ways
        in which the vomeronasal organ
        and the main olfactory systern
        process chemicals.

A主要比较了VNO和olfactory，和pheromone无关。

B.       summarize the debate over the
        role the vomeronasal organ plays in odor perception

B 总结了关于VNO在嗅觉分辨中的作用和角色，和pheromone无关。

C.      present some of the issues
        involved in the debate over
        what constitutes a pheromone

C是”提出了关于pheromone组成成分（what constitutes a pheromone），和所说的定义混淆无关。

D.      propose a new definition of
        pheromones based on recent
        research

D是“提出了一个基于最近研究发现的pheromone的定义”，但是原文恰恰是说没有清楚的定义，所以错误。

E.       argue that pheromones should be
        classified as a type of odorant

E是“长岛关于应该将pheromone归为一类odorant”。看样子就这个比较相关，虽然也不是心目中最完美的答案。但是因为其他都不相关，所以就选这个了。。。

希望有用。