Macrophages are cells that play a role in the response of the immune system of mice and other mammal...

题目信息

Macrophages are cells that play a role in the response of the immune system of mice and other mammals to invasive organisms such as bacteria. Unlike other mice, mice that are genetically incapable of making these particular cells do not show elevated levels of nitrates when infected with bacteria.

The statements above, if true, provide the most support for which of the following conclusions?

A:Mice that are unable either to make macrophages or to make them in sufficient numbers will protect themselves from bacterial infections in some other way.

B:Mice that show elevated levels of nitrates can easily fight off most types of bacterial infections.

C:In mice, macrophages play a role in the production of nitrates or inhibit a process by which nitrates are broken down or otherwise eliminated.

D:When a healthy mouse becomes infected with an invasive organism, the number of macrophages in the mouse's body decreases.

E:Injections of nitrates into mice that lack macrophages will not enhance the ability of these animals' immune systems to fight off infection.

参考答案及共享解析

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正确答案： C:In mice, macrophages play a role in the production of nitrates or inhibit a process by which nitrates are broken down or otherwise eliminated.

Infer题，注意，不是Must be true的题，如果是must be true，没有一个选项是对的。

题目出的非常隐晦。答案是C，因为题干支持C比B多一些，也因为C比B说的可能更加严密一些。

背景：外界生物（比如细菌）侵犯时老鼠或人的免疫系统会有response。

Fact 1：macrophage在这个response里起到了作用。（没说是什么作用，比如是感应？还是fight off？没说。Admittedly, 这个事实是可以support B选项，但没有能够support C选项那么多。）

Fact 2：细菌感染时，如果老鼠没有macrophage，那么它就没有 N2 升高。

此Fact等价于：细菌感染时，如果老鼠有N2 升高，那么就一定有macrophage [等价的逆否命题，它支持了C选项：macrophage plays a role in increased N2，至于后半句说减少了N2的消耗，也是类似的。]

因此，这两个fact支持C选项的程度比支持B选项的要多。

A选项的内容没说，我们连这些老鼠能不能protect themselves都不知道，更不用说how to protect themselves了。

D说的和fact 1说的内容相反；E说的内容和fact 2说的内容相反。都不可以选。

笔记