Unformatted text preview: sest in meaning to ○require
6. The word they in the passage refers to ○valleys
7. The word prone in the passage is closest in meaning to ○adapted
8. According to paragraph 3, which of the following is true of trees in the middle and upper latitudes? ○Tree growth is negatively affected by the snow cover in valleys.
○Tree growth is greater in valleys than on ridges.
○Tree growth on ridges is not affected by highvelocity winds.
○Tree growth lasts longer in those latitudes than it does in the tropics.
Paragraph 4 在 There is still no universally agreedon explanation for why there should be such a dramatic cessation of tree growth at the upper timberline. Various environmental factors may play a role. Too much snow, for example, can smother trees, and avalanches and snow creep can damage or destroy them. Latelying snow reduces the effective growing season to the point where seedlings cannot establish themselves. Wind velocity also increases with altitude and may cause serious stress for trees, as is made evident by the deformed shapes at high altitudes . Some scientists have proposed that the presence of increasing levels of ultraviolet light with elevation may play a role, while browsing and grazing animals like the ibex may be another contributing factor. Probably the most important environmental factor is temperature, for if the growing season is too short and temperatures are too low, tree shoots and buds cannot mature sufficiently to survive the winter months.
9. Which of the sentences below best express the essential information in the highlighted sentence in the passage? In correct choices change the meaning in important ways or leave out essential information. ○Because of their deformed shapes at high altitudes, trees are not likely to be seriously harmed by the strong winds typical of those altitudes. ○As altitude increases, the velocity of winds increase, leading to a serious decrease in the number of trees found at high altitudes. ○The deformed shapes of trees at high altitudes show that wind velocity, which increase with altitude, can cause serious hardship for trees. ○Increased wind velocity at high altitudes deforms the shapes of trees, and this may cause serious stress for trees.
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10. In paragraph 4, what is the author’s main purpose in the discussion of the dramatic cessation of tree growth at the upper timberline? ○To argue that none of several environment factors that are believed to contribute to that phenomenon do in fact play a role in causing it. ○To argue in support of one particular explanation of that phenomenon against several competing explanations. ○To explain why the primary environmental factor responsible for that phenomenon has not yet been identified. ○To present several environmental factors that may contribute to a satisfactory explanation of that phenomenon.
Paragraph 6 在 The most striking characteristic of the plants of the alpine zone is...
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This note was uploaded on 09/17/2013 for the course LANGUAGE 13DL208 taught by Professor Wang during the Fall '13 term at East China Normal University.
- Fall '13