2772-GRE90年4月sectionA

kuuiytt

Because of its accuracy in outlining the Earth’s subsurface, the seismic-reflection method remains the most important tool in the search for petroleum reserves (petroleum reserves: 石油储量). In field practice, a subsurface is mapped by arranging a series of wave-train sources, such as small dynamite explosions, in a grid pattern. As each source is activated, it generates a wave train that moves downward at a speed determined uniquely by the rock’s elastic characteristics. As rock interfaces are crossed, the elastic characteristics encountered generally change abruptly, which causes part of the energy to be reflected back to the surface, where it is recorded by seismic instruments. The seismic records must be processed to correct for positional differences between the source and the receiver, for unrelated wave trains, and for multiple reflections from the rock interfaces. Then the data acquired at each of the specific source locations are combined to generate a physical profile of the subsurface, which can eventually be used to select targets for drilling.

19. It can be inferred from the passage that the seismic-reflection method would be likely to yield an inaccurate physical profile of the subsurface in which of the following circumstances?

(A) If the speed at which the wave train moved downward changed

(B) If the receiver were not positioned directly at the wave-train source

(C) If the rock on one side of a rock interface had similar elastic characteristics to those of the rock on the other side

(D) If the seismic records obtained for the different sources in a grid were highly similar to each other（C）

(E) If there were no petroleum deposits beneath the area defined by the grid of wave-train sources

这道题我定位The seismic records must be processed to correct for positional differences between the source and the receiver, for unrelated wave trains, and for multiple reflections from the rock interfaces.为什么答案不是B？

开若兰

QUOTE:

以下是引用kuuiytt在2004-8-10 6:45:00的发言：
Because of its accuracy in outlining the Earth’s subsurface, the seismic-reflection method remains the most important tool in the search for petroleum reserves (petroleum reserves: 石油储量). In field practice, a subsurface is mapped by arranging a series of wave-train sources, such as small dynamite explosions, in a grid pattern. As each source is activated, it generates a wave train that moves downward at a speed determined uniquely by the rock’s elastic characteristics. As rock interfaces are crossed, the elastic characteristics encountered generally change abruptly, which causes part of the energy to be reflected back to the surface, where it is recorded by seismic instruments. The seismic records must be processed to correct for positional differences between the source and the receiver, for unrelated wave trains, and for multiple reflections from the rock interfaces. Then the data acquired at each of the specific source locations are combined to generate a physical profile of the subsurface, which can eventually be used to select targets for drilling.

19. It can be inferred from the passage that the seismic-reflection method would be likely to yield an inaccurate physical profile of the subsurface in which of the following circumstances?

(A) If the speed at which the wave train moved downward changed

(B) If the receiver were not positioned directly at the wave-train source

(C) If the rock on one side of a rock interface had similar elastic characteristics to those of the rock on the other side

(D) If the seismic records obtained for the different sources in a grid were highly similar to each other（C）

(E) If there were no petroleum deposits beneath the area defined by the grid of wave-train sources

这道题我定位The seismic records must be processed to correct for positional differences between the source and the receiver, for unrelated wave trains, and for multiple reflections from the rock interfaces.为什么答案不是B？

在 http://bbs.gter.net/bbs/thread-185790-1-1.html 上找到下面的解答。

 

A）第12－18行说“速度由岩石的弹性特征（elastic characteristics）唯一决定，当地震波穿越岩石界面时，弹性特征突然改变，导致地震波反射回地面”，也就是说弹性特征改变，则速度改变，只有这样才能产生反射，因此不会产生错误，故错。
B）文中并没有说接收器一定要放在震源处才正确，故错。

C）要求对13－18行的精确理解：“当穿越岩石界面时”，这里的岩石界面指两块岩石结合面；“弹性特征突然发生改变，导致地震波反射回地面”，也就是说好比上面的岩石软点，下面的岩石硬点，于是地震波在穿越软岩石后被硬岩石反射回去了，由此可以推知，如果两块岩石的弹性特征相似，那么地震波在穿越岩石界面时好像仍在一块岩石中穿行，没有任何的改变，不会被反射回去，导致了不正确的地质结构的描绘。故正确。

D）如果不同震源的结果很像，只能说明地质结构相似，这是客观事实，不能说是不正确的结果，故错。
E）没有石油是客观情况，最多换个地方继续炸，不能说没有测到石油就说明结果不正确，故错。

开若兰

QUOTE:

以下是引用kuuiytt在2004-8-10 6:45:00的发言：
Because of its accuracy in outlining the Earth’s subsurface, the seismic-reflection method remains the most important tool in the search for petroleum reserves (petroleum reserves: 石油储量). In field practice, a subsurface is mapped by arranging a series of wave-train sources, such as small dynamite explosions, in a grid pattern. As each source is activated, it generates a wave train that moves downward at a speed determined uniquely by the rock’s elastic characteristics. As rock interfaces are crossed, the elastic characteristics encountered generally change abruptly, which causes part of the energy to be reflected back to the surface, where it is recorded by seismic instruments. The seismic records must be processed to correct for positional differences between the source and the receiver, for unrelated wave trains, and for multiple reflections from the rock interfaces. Then the data acquired at each of the specific source locations are combined to generate a physical profile of the subsurface, which can eventually be used to select targets for drilling.

19. It can be inferred from the passage that the seismic-reflection method would be likely to yield an inaccurate physical profile of the subsurface in which of the following circumstances?

(A) If the speed at which the wave train moved downward changed

(B) If the receiver were not positioned directly at the wave-train source

(C) If the rock on one side of a rock interface had similar elastic characteristics to those of the rock on the other side

(D) If the seismic records obtained for the different sources in a grid were highly similar to each other（C）

(E) If there were no petroleum deposits beneath the area defined by the grid of wave-train sources

这道题我定位The seismic records must be processed to correct for positional differences between the source and the receiver, for unrelated wave trains, and for multiple reflections from the rock interfaces.为什么答案不是B？

这道题我也不明白参考答案为什么是 (C)。请高手发言。

ppp1

Modern archaeological finds can still contribute much to the study of ancient literature. For example, forty years ago a survey of the early Greek dramatist Aeschylus’ plays would have started with The Suppliant Women. Many factors internal to the play, but perhaps most especially the prominence of the chorus (which in this play has the main role), led scholars to consider it one of Aeschylus’ earlier works. The consensus was that here was a drama truly reflecting an early stage in the evolution of tragedy out of choral lyric. The play was dated as early as the 490’s B.C., in any event (in any event: 无论如何), well before Aeschylus’ play The Persians of 472 B.C. Then, in 1952, a fragment of papyrus found at Oxyrhynchus was published stating the official circumstances and results of a dramatic contest. The fragment announced that Aeschylus won first prize with his Danaid tetralogy, of which The Suppliant Women is the opening play, and defeated Sophocles in the process. Sophocles did not compete in any dramatic contest before 468 B.C., when he won his first victory. Hence, except by special pleading (e. g., that the tetralogy was composed early in Aeschylus’ career but not produced until the 460’s B.C.), the Danaid tetralogy must be put after 468 B.C. In addition, a few letters in the fragment suggest the name Archedemides, archon in 463 B.C., thus perhaps tying the plays to that precise date, almost exactly halfway between Aeschylus’ Seven Against Thebes of 467 B.C. and his Oresteia.

The implication of the papyrus administered a severe shock to the vast majority of classical scholars, who had confidently asserted that not only the role of the chorus but also language, metrics, and characterization all pointed to an early date. The discovery has resulted in no less than a total reevaluation of every chronological criterion that has been applied to or derived from Aeschylus’ plays. , and a new creed has now spread. The prominence of the chorus in The Suppliant Women now is seen not as a sign of primitivism but as analogous to the massive choral songs of the Oresteia. Statistics have been formulated, or reformulated, to show that stylistically The Suppliant Women does actually occupy a position after The Persians and Seven Against Thebes, which now become the “primitive” plays, and before the Oresteia. While the new doctrine seems almost certainly correct, the one papyrus fragment raises the specter that another may be unearthed, showing, for instance, that it was a posthumous production of the Danaid tetralogy which bested Sophocles, and throwing the date once more into utter confusion. This is unlikely to happen, but it warns us that perhaps the most salutary feature of the papyrus scrap is its message of the extreme difficulty of classifying and categorizing rigidly the development of a creative artist.

该题是否从The activity has been brisk定位

26. The author’s attitude toward the “activity” mentioned in line 35 and its consequences can best be described as one of

(A) amused tolerance

(B) mocking envy

(C) grave doubt

(D) angry disapproval（A）

(E) unrestrained enthusiasm