TPO60阅读真题+题目+答案下载：Earth' s Core

前两篇阅读真题，请点击：

TPO60阅读真题+题目+答案下载：Underground Life

TPO60阅读真题+题目+答案下载：The Revolution of Cheap Print

TPO60阅读真题+题目+答案下载：Earth' s Core

[ Paragraph 1 ] Knowledge of Earth' s deep interior is derived from the study of the waves produced by earthquakes, called seismic waves Among the various kinds of seismic waves are primary waves (P -waves) and secondary waves (Swaves). Primary and secondary waves pass deep within Earth and therefore are the most instructive. Study of abrupt changes in the characteristics of seismic waves at different depths provides the basis forat hreefold division of Earth into a central core; a thick, overlying mantle: and a thin, enveloping crust. Sudden changes in seismic wave velocities and angles of transmission are termed discontinuities.

1. The word "instructive" in the passage is closest in meaning to

A. inaccurate

B. intense

C. inaccessible

D. informative

2. According to paragraph 1, which of the following findings provides the basis for Earth' s division into three parts?

A. All seismic waves pass deep within Earth.

B. There are no significant differences in the behavior of P-waves and S-waves.

C. Discontinuities occur at different depths within Earth

D. Earth' s crust is too thin to account for the size of the planet.

[ Paragraph 2 ] One of the discontinuities is the Gutenberg discontinuity, which is located nearly halfway to the center of Earth at a depth of 2,900 kilometers and marks the outer boundary of Earth's core. At that depth, the S-waves cannot propagate, while at the same time P-wave velocity is drastically reduced S-waves are unable to travel through fluids. Thus, if S-waves were to encounter a fluidlike region of Earth' s interior, they would be absorbed there and would not be able to continue. Geophysicists believe this is what happens to S-waves as they enter the outer core. As a result, the S-waves generated on one side of Earth fail to appear at seismograph stations on the opposite side of Earth, and this observation is the principal evidence of an outer core that behaves as a fluid. Unlike S-waves, P-waves are able to pass through liquids They are, however, abruptly slowed and sharply refracted (bent) as they enter a fluid medium. Therefore, as P-waves encounter the molten outer core of Earth, their velocity is reduced and they are refracted downward。

3. The word "drastically" in the passage is closest in meaning to

A. gradually

B. severely

C. typically

D. permanently

4. The word "abruptly" in the passage is closest in meaning to

A. suddenly

B. eventually

C. smoothly

D. normally

[ Paragraph 3 ] The radius of the core is about 3,500 kilometers. The inner core is solid and has a radius of about 1,220 kilometers, which makes this inner core slightly larger than the Moon. Most geologists believe that the inner core has the same composition as the outer core and that it can only exist as a solid because of the enormous pressure at the center of Earth. Evidence of the existence of a solid inner core is derived from the study of hundreds of records of seismic waves produced over several years. These studies showed that the inner core behaves seismically as if it were a solid.

以下原文已省略！

完整版TPO60阅读(3篇)原文+题目+答案下载，5元有偿!