黃金閱讀TIMBERLINE VEGETATION ON MOUNTAINS - 英檢

第13篇

第4段: There is no universally ageed-on explanation for why there should be
such a dramatic cessation of tree growth at the upper timberline. Various
enviromental factors may play a role. Too much snow, for example, can smother
trees, and avalanches and snow creep can damage or destroy them. Late-lying
snow reduces the effective growing season to the point where seedling cannot
establish themselves. Wind velocity aslo increases with altitude and may cause
serious stress for trees, as is made evident by the deformed shapes at high
altitudes. Some scientists have porposed that the presence of increasing
levels of ultraviolet light with elevation may play a role, while browsing and
grazing animals like the ibox may be another contributing factor. Probably
the most important envirometal 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.

第10題 In paragraph 4, what is the author's main prupose in the discussion of
the dramatic cessation of tree growth at the upper timberline?

2)To argue in support of one particular explanation of that phenomenon against
several competingexplanations.

4)To present several enviromental factors that may contribute to a
satisfactory explanaiton of that phenomenon.

想問答題關鍵是不是黃色那句?

但不能根據最後一句，尤其是藍色部分，來選2嗎?
如果不能選是不是因為多了個enviromental而局部化了這個描述@?@

想再問看看最後的配合題6選3，其中一個是:
There is no agreement among scientists as to exactly why plant growth is
sharply different above and below the upper timberline.
這選項的關鍵也剛好就是第4段嗎?
是的話就跟上面是同一個意思?

不過還是想知道為啥不能根據紅色區段選答案~"~

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