2015年9月20日的GRE考试就快到了，为了让大家准备更充分地迎接9月20日的GRE考试，下面为大家整理了2015年9月20日GRE逻辑机经预测 ，欢迎参考。

　　2015年9月20日GRE逻辑机经预测：

　　Upon maturity, monarch butterflies travel hundreds of miles from their places of origin and lay their eggs on milkweed. The caterpillars that emerge feed on milkweed and absorb the glycosides in milkweed sap. The specific glycosides present in milkweed differ from region to region within the monarch butterfly’s range. Mature butterflies retain the glycosides in a mature monarch butterfly could be used to determine its place of origin. Which of the following, if true, most strengthens the argument?

　　A. Mature monarch butterflies do not feed on parts of milkweed that contain glycosides.

　　B. The glycosides in milkweed sap are slightly toxic to caterpillars of other species.

　　C. The vast majority of the monarch butterflies that are laying eggs in a given region will have traveled there from a single region.

　　D. There are substances other than glycosides in milkweed sap that accumulate in a monarch caterpillar and are retained in the body of the mature butterfly.

　　E. There are certain glycosides that are found in the sap of all milkweeds, no matter where they grow within the monarch butterfly’s range.

　　答案：C

　　只有C 选项是加强了上文的论点。

　　A cave in Central America was occupied by humans for much of the period from 9,000 to 500 years ago. Archaeological excavations in the cave have discovered remains of food plants at every level of habitation, increasing from fewer than ten food plant species in the earliest (lowest) levels to over 30 species in the latest levels. Clearly, later inhabitants of the cave used a greater variety of plants as food than earlier inhabitants did.

　　Which of the following, if true of the cave, most weakens the argument?

　　(A) Some of the plant species found in the earlier (lower) levels of habitation are not found at all in the later (upper) levels of habitation.

　　(B) The remains of some plant species, such as squash and chili peppers, show changes from the middle to the later (upper) levels that indicate domestication.

　　(C) At certain points during the period from 9,000 to 500 years ago, the cave was abandoned for a time and later reoccupied by people who were probably of a different culture than the earlier inhabitants

　　(D) Virtually all the plant remains found at earliest (lowest) levels of habitation are tough fibers that are relatively resistant to decomposition.

　　(E) The total volume of food plant remains found in the earlier (lower) layers was greater than that found in the later (upper) layers.

　　参考答案：D

　　Avionics is a portmanteau word meaning “aviation electronics.” It is a term that has evolved over the last 40 years as airplane instrumentation has evolved from mostly mechanical to largely electronic. Today, avionics makes up the large part of the cost of any aircraft. Guidance and navigation systems are integrated. Communications includes public address systems for communicating with passengers, intercoms for communicating with flight crews, and radio or SatCom for communicating with ground personnel. In addition, planes today have weather radar, lightning detectors, automatic flight control systems, and collision-avoidance systems. All of these systems must work in tandem in order for the plane to fly.

　　Select one answer choice.

　　Which of the following inferences about avionics is best supported by the passage?

　　(A) Within a decade, passenger planes will take off and land without human intervention.

　　(B) Soon passenger planes will include features that now appear only on military planes.

　　(C) Just 40 years ago, there were no electronic devices on passenger airplanes.

　　(D) As avionics becomes more common, the cost of manufacturing planes will decrease.

　　(E) A glitch in a plane's electrical system may be the greatest danger in flight today. 参考答案：E.

　　Many shipwrecks dating from the period between A D. 300 and 600 have been discovered in the Ramian Sea. Well over half of those ships were carrying cargo stored in large ceramic jars, many of which were preserved largely intact on the ocean floor. During that period, such jars carried only liquid. Therefore, liquid cargo was probably carried by a majority of the cargo ships that navigated the Ramian Sea during that period.

　　The force of the evidence cites in the passage is most seriously weakened if which of the following is true?

　　For ships on the Ramian Sea during the period, a full load ofliquid cargo stored in large ceramic jars was not likely to be significantly heavier than a full load of other kinds of cargo that were typical of the period.

　　There are no surviving records dating from the period that detail specific cargoes shipped across the Ramian Sea.

　　The ratio ofliquid to solid cargo shipped across the Ramian Sea did not vary significantly over the period.

　　The presence of a sizable quantity of large ceramic jars on the ocean floor is so visually striking that a shipwreck of a ship carrying such jars is more likely to be noticed and reported than are shipwrecks of ships carrying other cargoes.

　　During the period, grain and other solid cargo was shipped across the Ramian Sea in containers made from material other than clay.

　　参考答案：D