陈虎平阅读exercise18 8

AnnieZhuo

At the Shadybrook dog kennel, all the adult animals were
given a new medication designed to reduce a dog‘s risk of
contracting a certain common infection. Several days after
the medication was administered, most of the puppies of
these dogs had elevated temperatures. Since raised body
temperature is a side effect of this medication, the kennel
owner hypothesized that the puppies‘ elevated temperatures
resulted from the medication‘s being passed to them
through their mothers‘ milk.

8.
Which of the following, if true, provides the most
support for the kennel owner‘s hypothesis?
(A) Some puppies have been given the new medication
directly but have not suffered elevated
temperatures as a side effect.
(B) The new medication has been well received by dog
breeders as a safe and effective way of preventing
the spread of certain common canine infections.
(C) None of the four puppies in the kennel who had
been bottle-fed with formula had elevated
temperatures.
(D) an elevated temperature is a side effect of a
number of medications for dogs other than the new
medication administered at the kennel.
(E) Elevated temperatures such as those suffered by
most of the puppies in the kennel rarely have
serious long-term effects on a puppy‘s health.


答案是E...我选C。。。。

AnnieZhuo

还有exercise 14
In electrides, the anions (negative ions) are
completely replaced by electrons, which are trapped in
naturally formed cavities within a framework of regularly
stacked cations (positive ions). Unlike other types of
anions, anionic electrons do not behave as if they were
simple charged spheres. The properties of an electride
depend largely on the distance between the cavities that
hold trapped electrons. When the trapped electrons are far
apart, they do not interact strongly, and so behave
somewhat like an array of isolated negative charges.
When they are closer together, they begin to display
properties associated with large ensembles of identical
particles. When they are still closer, the ensemble
properties dominate and the electrons "delocalize".

12. It can be inferred from the passage that an electride
behaves most like a normal ionic crystal when the
electride has which of the following features?
(A) The anionic cavities are widely separated.
(B) All of the trapped electrons are able to delocalize.
(C) The trapped electrons are liberated by
impinging photons.
(D) The ions are tightly packed together.
(E) Most of the cations have lost their electrical
charge.

gqwphoenix

第一题就应该是c，虎平老师改过答案。。。

第二题是不是选 a 啊，（的越近越变态。。。） 不知你的问题？

AnnieZhuo

gqwphoenix 发表于 2013-4-12 12:47
第一题就应该是c，虎平老师改过答案。。。

第二题是不是选 a 啊，（的越近越变态。。。） 不知你的问题？ ...

谢谢~~！

第二题是选A。。可是为什么啊文章里都没有提到crystal这个东西

gqwphoenix

AnnieZhuo 发表于 2013-4-12 13:56
谢谢~~！

第二题是选A。。可是为什么啊文章里都没有提到crystal这个东西

这是老g长文，被改编后不太完整了。。。
One of the simplest and best known kinds of crystal is the ionic salt, of which a typical example is sodium chloride or ordinary table salt. The fundamental components of an ionic salt are ions: atoms or molecules that have become electrically charged by gaining or losing one or more electrons. In forming sodium chloride, for example, sodium atoms give up an electron (thereby becoming positively charged) and chlorine atoms gain an electron (thereby becoming negatively charged). The ions are attracted to one another by their opposite charges, and they stack together compactly, like tightly packed spheres.
Recently, scientists at Michigan State University created a new kind of crystal called an electride. In electrides, the anions (negative ions) are completely replaced by electrons, which are trapped in naturally formed cavities within a framework of regularly stacked cations (positive ions). Electrides are the first examples of ionic salts in which all these anionic sites are occupied solely by electrons.
Unlike other types of anions, anionic electrons do not behave as if they were simple charged spheres. In particular, because of their low mass and their tendency to interact with one another over great distances, they cannot be “pinned down” to any one location. Instead, they wander close to and among the atoms lining the cavity and interact with electrons in nearby cavities, perhaps changing places with them.
The properties of an electride depend largely on the distance between the cavities that hold trapped electrons. When the trapped electrons are far apart, they do not interact strongly, and so behave somewhat like an array of isolated negative charges. When they are closer together, they begin to display properties associated with large ensembles of identical particles. When they are still closer, the ensemble properties dominate and the electrons “delocalize”: they are no longer tightly bound within individual cavities but are more or less free to pass through the spaces within the frame-work of positive ions.
By synthesizing electrides from a variety of materials, one can vary the geometry of the anionic cavities and their relation to the surrounding cations. The resulting properties may make it possible for electrides to become a basis for economically useful new materials and devices. For instance, because the electrons in some electrides are very weakly bound, these crystals could be effective as photosensitive detectors, in which an impinging photon liberates an electron, resulting in a small electric current. The same weak binding could also make electrides useful in solar-energy converters and as cathodes in batteries. One obstacle is the tendency of electrides to decompose through reaction with air and water. Researchers are seeking ways to increase their stability.