The upper timberline, like the snow line, is highest in the tropics and lowest in the Polar Regions. It ranges from sea level in the Polar Regions to 4,500 meters in the dry subtropics and 3,500-4,500 meters in the moist tropics. Timberline trees are normally evergreens, suggesting that these have some advantage over deciduous trees (those that lose their leaves) in the extreme environments of the upper timberline. There are some areas, however, where broadleaf deciduous trees form the timberline. Species of birch, for example, may occur at the timberline in parts of the Himalayas.
Timberline trees are normally evergreens, suggesting that these have some advantage over deciduous trees (those that lose their leaves) in the extreme environments of the upper timberline.
树带界限的树木通常都是常青树，这表明（在树带界限上部的极端条件下）树带界限的树比落叶树要有优势
Timberline trees are normally evergreens, suggesting that Timberline trees have some advantage over deciduous trees (those that lose their leaves) in the extreme environments of the upper timberline.
Timberline trees have some advantage over deciduous trees (those that lose their leaves) in the extreme environments of the upper timberline.
Timberline trees have some advantage but deciduous trees not.
To be in a favorable or superior position when compared to someone or something else. That team has so many injuries right now that I think we have the advantage over them.
第4题：Paragraph 2 supports which of the following statements about deciduous trees?
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A.They cannot grow in cold climates.------错误，没提及cold
B. They do not exist at the upper timberline.----错误，不是deciduous trees不在upper timberline中，而是Timberline trees 和deciduous trees 都在upper timberline中。
C. They are less likely than evergreens to survive at the upper timberline.
D. They do not require as much moisture as evergreens do.---错误，不是比较水分，而是没有明确说明。
