【正文】 s surface. (B) The nucleus of the et expanded. (C) The tail of the et straightened out. (D) Jets of gas caused the et to increase its speed. 17. All of the following statements about the tails of ets are true EXCEPT: (A) They can contain electrically charged or neutral particles. (B) They can be formed only when there is sufficient heat. (C) They are formed before the a expands. (D) They always point in the direction away from the Sun. 18. The word distinct in line 17 is closest in meaning to (A) visible (B) gaseous (C) separate (D) new 19. Compared to the tail of electrically charged atoms, the tail of neutral dust particles is relatively (A) long (B) curved (C) unpredictable (D) bright Questions 2029 Many prehistoric people subsisted as hunters and gatherers. Undoubtedly, game animals, including some very large species, provided major ponents of human diets. An important controversy centering on the question of human effects on prehistoric wildlife Line concerns the sudden disappearance of so many species of large animals at or near the end (5) of the Pleistocene epoch. Most paleontologists suspect that abrupt changes in climate led to the mass extinctions. Others, however, have concluded that prehistoric people drove many of those species to extinction through overhunting. In their Pleistocene overkill hypothesis, they cite what seems to be a remarkable coincidence between the arrival of prehistoric peoples in North and South America and the time during which mammoths, (10) giant ground sloths, the giant bison, and numerous other large mammals became extinct. Perhaps the human species was driving others to extinction long before the dawn of history. Huntergatherers may have contributed to Pleistocene extinctions in more indirect ways. Besides overhunting, at least three other kinds of effects have been suggested: direct petition, imbalances between peting species of game animals, and early (15) agricultural practices. Direct petition may have brought about the demise of large carnivores such as the sabertoothed cats. These animals simply may have been unable to pete with the increasingly sophisticated hunting skills of Pleistocene people. Human hunters could have caused imbalances among game animals, leading to the 10 extinctions of species less able to pete. When other predators such as the gray wolf (20) prey upon large mammals, they generally take high proportions of each year s crop of young. Some human hunters, in contrast, tend to take the various agegroups of large animals in proportion to their actual occurrence. If such hunters first peted with the larger predators and then replaced them. they may have allowed more young to survive each year, gradually increasing the populations of favored species As these populations expanded, (25) they in turn may have peted with other game species for the same environmental niche, forcing the less hunted species into extinction. This theory, suggests that human hunters played an indirect role in Pleistocene extinctions by hunting one species more than another. 20. What does the passage mainly discuss? (A) The effects of human activities on prehistoric wildlife (B) The origins of the huntergatherer way of life (C) The diets of large animals of the Pleistocene epoch (D) The change in climate at the end of the Pleistocene epoch 21. The word Undoubtedly in line I is closest in meaning to (A) occasionally (B) unexpectedly (C) previously (D) certainly 22. The word ponents in line 2 is closest in meaning to (A) parts (B) problems (C) changes (D) varieties 23. Which of the following is mentioned as supporting the Pleistocene overkill hypothesis? (A) Many of the animals that became extinct were quite large. (B) Humans migrated into certain regions around the time that major extinctions occurred. (C) There is evidence that new species were arriving in areas inhabited by humans. (D) Humans began to keep and care for certain animals. 24. The word Besides in line 13 is closest in meaning to (A) caused by (B) whereas (C) in addition to (D) in favor of 25. The author mentions sabertoothed cats in line 16 as an example of a carnivore that (A) became extinct before the Pleistocene epoch (B) was unusually large for its time (C) was not able to pete with humans (D) caused the extinction of several species 26. The word they in line 20 refers to (A) human hunters (B) game animals (C) other predators (D) large mammals 27. According to the passage, what is one difference between the hunting done by some humans and the hunting done by gray wolves? (A) Some humans hunt more frequently than gray wolves. (B) Gray wolves h。s nucleus. 14. It can be inferred from the passage that the nucleus of a et is made up of (A) dust and gas (B) ice and dust (C) hydrogen gas (D) electrically charged atoms 15. The word graphic in line 9 is closest in meaning to (A) mathematical (B) popular (C) unusual (D) vivid 16. Which of the following occurred as the ices from Halley39。s Comet. It turned out to be a bit like a very dark asteroid, measuring 16 by 8 kilometers. Ices have evaporated from its outer layers to leave a crust of nearly black dust all over the surface. Bright jets of gas from evaporating ice burst out on the side facing the Sun, where the surface gets heated up, carrying dust (15) with them. This is how the a and the tails are created. Comets grow tails only when they get warm enough for ice and dust to boil off. As a et39。s seeking advice from another firm. 7. According to the passage, when was the Olmsted Report officially accepted as the master plan for the Seattle public park system? (A) 1903 (B) 1907 (C) 1909 (D) 1913 8. The word sums in line 20 is clos