Reading

Passage 1

Topic

The Role of Diapause （生物类）

Content Review

段介绍了diapause，先是介绍了dia 具体是什么个情况，然后说到了他的好处。

第二段开始说导致dia的两种情况，一种是unfavorable condition， 另一种是unpredicted condition。 然后说 第二种condition 比起种对生物的影响更大。然后引出问题：动物是怎么样去度过 unpredictable condition的。

第三段举了一个具体的red beast的例子，这种动物延长baby在pouch的时间，连续三次生完之后即可mate，通过在同一个时间段生三个宝宝的方法来去度过这个困难的时期。

第四段说到另一种动物在雨季的时候出来集体配对 然后通过加速孵化，一般为3-4；然后在宝宝浮出声大概十六天左右就立马跑回地底下去避暑。然后下一次在下雨的季节再出来交配。

Passage 2

Topic

Milankovitch Cycles and Glaciation（地理地质类）

（重复17年3月25真题，2014年05月24日大陆真题）

Content Review

  Milankovitch Cycles and Glaciation

Paragraph1：Although the history of glaciation during the Pleistocene epoch (2 million to 10,000 years ago) is well established, we do not know with complete certainty why glaciation takes place. For over a century, geologists and climatologists have struggled with this problem, but it remains unsolved.

Paragraph2：It is long known that Earth’s orbit around the Sun changes periodically, cyclically affecting the way solar radiation strikes the Earth, but the idea that these changes affect climate was first advanced by James Croll in the late 1800s. Later, Milutin Milankovitch elaborated the theory with calculations that convincingly argued that the cycles, now known as Milankovitch cycles, could cause climatic variations.

Paragraph3：The Milankovitch cycles emerge from the way three cyclic changes in Earth’s orbit combine. One characteristic of Earth’s orbit is its eccentricity, the degree to which the orbit is an ellipse rather than a circle. Changes in the eccentricity of Earth’s orbit occur in a cycle of about 96,000 years. The inclination, or tilt, of Earth’s axis also varies periodically, moving between 22 degrees and 24.5 degrees. The tilt of Earth’s axis, toward the Sun at some times of the year and away from the Sun at other times, is responsible for the annual cycle of seasons. The greater the tilt, the greater the contrast between summer and winter temperatures. Changes in the tilt occur in a cycle 41,000 years long. Also, Earth wobbles as it spins, like a slightly unsteady top. The wobble cycle is completed once every 21,700 years. Changes in eccentricity, tilt and wobble do not affect the total amount of solar radiation Earth receives in a year, but they do affect how evenly or unevenly this radiation is disturbed over the course of a year. According to the Milankovitch theory, about every 40,000 years the three separate cycles combine in such a way that the difference between summer and winter temperatures is at a minimum. At this point winter temperatures are milder but so too are summer temperatures. As a result, less ice is melted in the summer than is formed in the winter, so glaciers build up and a period of glaciation results.

Paragraph4：Milankovitch worked out the ideas of climatic cycles in the 1920s and 1930s, but it was not until the 1970s that a detailed chronology of the Pleistocene temperature changes was determined that could test the predictions of this theory. A correspondence between Milankovitch cycles and climate fluctuations of the last 65 million years seems clear. Furthermore, studies or rock samples drilled from the deep-sea floor and the fossils contained in them indicate that the fluctuation of climate during the past few hundred thousand years is remarkably close to that predicted by Milankovitch.

A problem with Milankovitch’s explanation of glaciation arises from the fact that the variations in Earth’s orbit, and hence the Milankovitch cycles, have existed for billions of years. Thus we might expect that glaciation would have been a cyclic event throughout geologic time. In fact, periods of glaciation are rare. So there must be another factor acting together with the Milankovitch cycles that causes periods of glaciation. Once this additional factor makes the temperature low enough, the cyclic variations of the Milankovitch cycles will force the planet into and out of glacial epochs with a fixed regularity.

Paragraph5：Many hypotheses have been proposed for the additional cooling factor. Some suggest that variations in the Sun’s energy output could account for the ice ages. However, our present understanding of the Sun’s luminosity holds that it should have progressively increased, not decreased, over the course of Earth’s history. Still others argue that volcanic dust injected into the atmosphere shields Earth from the Sun’s rays and initiates an ice age. However, no correlation has been found between volcanic activity and the start of the last ice age. An increasingly attractive theory holds that decreases in atmospheric carbon dioxide starts the cooling trend that leads to glaciation. Carbon dioxide traps solar energy reflected from the Earth’s surface. If carbon dioxide levels decrease, less heat is trapped and Earth’s surface cools. Recent studies of the carbon dioxide content of gas bubbles preserved in the Greenland ice cap do in fact show that high carbon dioxide levels are associated with warm interglacial periods, and low levels with cold glacial periods.

其中词汇题为：

elaborated=developed

remarkably close=extremely close

initiates=begins

Passage 3

Topic

Egyptian and Mesopotamian(人文历史类）

Content Review

2017.03.04的首考新题，并在2017.07.02和2017.11.18两次被重复考查。主要讲美索不达米亚人和埃及人的主要区别。

本文主要讲美索不达米亚人和埃及人的主要区别。

前三段在讲m的城市，决定市中心的位置和大小主要取决于时候能从别的城市获得食物的能力，因此在市中心人口最多，城市的人口分布不均匀；不同城市之间的间隔是由城墙来区别的；主要的business是手工艺品。

后两段讲的是埃及，埃及的城市是均匀分布的，分布在尼罗河附近，大家都有相对均衡的资源来源，不同城市之间不需要有竞争；埃及的主要生意来源是trading and shipping，因为靠着河岸边有很多港口；不同小城市之间不需要由城墙去区分开来，大家生活的都很融洽。

Passage 4

Topic

生物类

Content Review

讲了有社会化结构的昆虫,这种结构让他们内部分工效率化,虽然有的作为 labor寿命短也不生孩子，但是对其他后代有很大的帮助是非常无私的。然后这种结构还可以让他们同时监督领地内外的工作活动,信息传递更快,找到食物以后搬回来更快。这种社会化结构的昆虫包括蚂蚁蜜蜂只占有所有昆虫 species的2%但是确 dominant。最后举了两种蚂蚁作为例子,一个是用叶子做巢一个是可以打败其他小动物的蚂蚁。

Passage 5

Topic

人文历史类

Content Review

讲了二次工业革命的事情,主要是因为工业革命给 workers 带来了一些变故, unskil 的工作机器都能做了。然后工业革命给经历了次工业革命的国家带来的变故,煤矿开采越来越少了，因为有了 engine， 然后工业革命带来了不仅是纺织业还有其他行业的发展,连家务活都能用机器做,最后说的是工业革命在美国福克斯公司生产线的体现,工人开始做一些不用动脑子的工作。

Passage 6

Topic

地理地质类

Content Review

讲了一个PEME貌似是这个时期的海洋变化,里面的碳原子比例变了,有科学家猜测是因为甲烷大量从海底释放,(这里有个问题是要很多很多的甲烷才能导致这样的结果)这种固态甲烷像冰一样,只能特定的 pressure 和温度下存在,所以就开始猜测什么原因导致他的释放,有人说海底升温,还有两个其他的原因。

Passage 7

Topic

人文历史类

Content Review

新大陆移民交易对印第安人生活的影响

Passage 8

Topic

天文学类

Content Review

火星曾经有没有水，NASA等机构到探测器在火星上开展的一系列发现其水源地的研究。

Passage 9

Topic

生物类

Content Review

讲动物的 resting stage先说种子 germinate在冬天快结束时开始动物有红袋鼠某种蟾蜍挖沙漠找阴暗潮湿的地方躲干燥环境在下雨时交配繁殖。