問題詳情

VII. Reading Comprehension   The ocean bottom ------a region nearly 2.5 times greater than the total land areaof the Earth ---- is a vast frontier that even today is largely unexplored and uncharted.Until about a century ago, the deep-ocean floor was completely inaccessible, hiddenbeneath waters averaging over 3,600 meters deep. Totally without light and subjected to intense pressures hundreds of times greater than at the Earth's surface, thedeep-ocean bottom is a hostile environment to humans, in some ways as forbiddingand remote as the void of outer space.    Although researchers have taken samples of deep-ocean rocks and sediments forover a century, the first detailed global investigation of the ocean bottom did notactually start until 1968, with the beginning of the National Science Foundation'sDeep Sea Drilling Project (DSDP). Using techniques first developed for the offshoreoil and gas industry, the DSDP's drill ship, the Glomar Challenger, was able tomaintain a steady position on the ocean's surface and drill in very deep waters,extracting samples of sediments and rock from the ocean floor.    The Glomar Challenger completed 96 voyages in a 15-year research programthat ended in November 1983. During this time, the vessel logged 600,000 kilometersand took almost 20,000 core samples of seabed sediments and rocks at 624 drillingsites around the world. The Glomar Challenger's core samples have allowedgeologists to reconstruct what the planet looked like hundred of millions of years agoand to calculate what it will probably look like millions of years in the future. Today,largely on the strength of evidence gathered during the Glomar Challenger's voyages,nearly all earth scientists agree on the theories of plate tectonics and continental driftthat explain many of the geological processes that shape the Earth.    The cores of sediment drilled by the Glomar Challenger have also yieldedinformation critical to understanding the world's past climates. Deep-ocean sedimentsprovide a climatic record stretching back hundreds of millions of years, because theyare largely isolated from the mechanical erosion and the intense chemical andbiological activity that rapidly destroy much land-based evidence of past climates.This record has already provided insights into the patterns and causes of past climaticchange --- information that may be used to predict future climates.
39.The author refers to the ocean bottom as a "frontier" in the 1st paragraph because it__________.
(A) is not a popular area for scientific research
(B) contains a wide variety of life forms
(C) attracts courageous explorers
(D) is an unknown territory

參考答案

答案：D
難度：適中0.5
統計：A(0),B(0),C(0),D(0),E(0)

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