[A] New plants and animals then move into the area and begin to grow. [B] Just 2

［A］Newplantsandanimalsthenmoveintotheareaandbegintogrow.

［B］Just2percentofthesunlightgoesthroughthemanylayersofleavesandbranchesabove,sounderstoryplantspecieshavedevelopedspecialtr aitstocopewithlowlightlevels.

［C］Onasmallerscale,largemammals,suchaselephants,regularlydestr oyrainforestvegetationintheCongoRiverBasininAfrica.

［D］Anunderstoryofshortertr eesandalaceworkofwoodyvines,orlianas,produceaforestofsuchcomplexinternalarchitecturethatmanyanimals,includingsomesizableones,rarelyorneverdescendtotheground.

［E］Lessthanonepercentofthetr eesintheforestr esideinthecanopyandemergentlayers.

［F］Becausemorelightpenetr atesthecanopy,however,thevegetationoftheunderstoryandforestfloorisbetterdevelopedthaninthetr opics.

［G］Therich,greencanopyisteemingwithlife,andforestr esearchershavedevelopedingeniousmethodsforaccessingthismysteriousecosystem.

 本题考查的知识点是：段落内一致性原则+上下文的衔接

本题空格出现在第一段中。上文提到热带雨林结构中的最低层是下层植被。下文提到，下层植被的植物叶子呈深红色，从而能够获取到达下层植被的少量的光。由此可见，上下文都围绕“下层植被”展开论述。出现关键词“understory”的选项有［B］、［D］和［F］。但是，［D］出现了上下文没有的新信息：“藤蔓植物”。［F］中出现了“冠层（canopy）”，但从下文即第一段倒数第二句对canopy一词的定义可知，它应在下文中第一次出现。由此排除［D］和［F］项。［B］强调下层植被适应低光强的特性，其中“低光强”与下文“获取少量的光”、“吸收不同波长的光”等内容相呼应。