题目解析：
【题目翻译】为什么作者在文章中提到“亚马逊河流域成熟的漫滩热带森林”？
A：对热带森林是分层排列的说法提出异议
B：举一个复杂建筑的例子，植被在一个密集的地区展示。
C：表明一些热带森林的树冠层可以超过通常的三到四层。
D：强调热带森林的树冠层提供了地下根组织层数的证据。
【判定题型】：根据题干问法“why …… mention”，题目询问“xxxxxx”(文章引用内容)的修辞目的，可以判断本题为修辞目的题。
【关键词定位】：根据关键词“mature floodplain tropical forest”,定位到Passage3，原句为“In a mature floodplain tropical forest in the Amazon River basin, the canopy (the uppermost layers of a forest, formed by the crowns of trees) takes on a stratified structure. There are three clear peaks in leaf cover at heights of approximately 3, 6, and 30 meters above the ground; and the very highest layer, at 50 meters, corresponds to the very tall trees that stand free of the main canopy and form an open layer of their own. So, such a forest contains essentially four layers of canopy. Forests in temperate lands often have just two canopy layers, so they have much less complex architecture.”。
【引用内容分析】根据原文可知文章提及亚马逊盆地丰富的泛滥平原热带雨林是为了说明其结构的复杂性。
【选项分析】
A.并未提出异议，故错误。
B.文中so they have much less complex architecture对应B选项中的an example of the complex architecture, 所以B选项正确。
C.与热带森林的树冠层无关。故错误。
D.与热带森林的树冠层无关。故错误。
Productivity seems to be involved instead, though perhaps its influence is indirect. Where conditions are most suitable for plant growth - that is, where temperatures are relatively high and uniform and where there is an ample supply of water - one usually finds large masses of vegetation. This leads to a complex structure in the layers of plant material In a tropical rain forest, for example, a very large quantity of plant material builds up above the surface of the ground. There is also a large mass of material, developed below ground as root tissues, but this is less apparent. Careful analysis of the above ground material reveals that it is arranged in a series of layers, the precise number of layers varying with age and the nature of the forest. The arrangement of the biological mass ("biomass") of the vegetation into layered forms is termed its “structure” (as opposed to its “composition”, which refers to the species of organisms forming the community). Structure is essentially the architecture of vegetation, and as in the case of tropical forests, it can be extremely complicated. In a mature floodplain tropical forest in the Amazon River basin , the canopy (the uppermost layers of a forest, formed by the crowns of trees) takes on a stratified structure. There are three clear peaks in leaf cover at heights of approximately 3, 6, and 30 meters above the ground; and the very highest layer, at 50 meters, corresponds to the very tall trees that stand free of the main canopy and form an open layer of their own. So, such a forest contains essentially four layers of canopy. Forests in temperate lands often have just two canopy layers, so they have much less complex architecture.
