阅读理解

      Peru(秘鲁)is the fifth largest Latin American country with a people of 14, 430, 000. Almost half of these people live in the city areas(地区). Around Lima, there were 20% of the total (总数) population in 1961. The population here grew faster than anywhere else and in another 35 years reached 1/3 of the total population.

      About 45% of the people are Indians and 50% are white or mixed（混合人种）and the others are Asians, Negroes(黑人)or people from other countries.

      In island areas, only about half of the people can read and write, but at the places near the sea, 2/3 of the people can read and write.

为探究不同条件对叶片中淀粉合成的影响，将某植物在黑暗中放置一段时间，耗尽叶片中的淀粉．然后取生理状态一致的叶片，平均分成8组，实验处理如下表所示．一段时间后，检测叶片中有无淀粉，结果如下表．

请回答下列问题：

（1）欲检测叶肉细胞中有无淀粉的生成，应先使用____ （填试剂名称）对叶片进行脱色处理，然后滴加____ （填试剂名称）进行检测，如叶片变为____色，说明叶肉细胞中产生了淀粉．

（2）与组5相比，组6无淀粉的原因是因为无光照，叶肉细胞缺少____ 和____ ，影响了暗反应进行．与组5相比，组7叶片无淀粉的原因是缺少____ ，影响了暗反应进行．

（3）组2叶片中合成淀粉的原料是____ ，直接能源物质是____ ，此时该直接能源物质产生的场所有____．如果组4的溶液中只通入N₂，预期实验结果是：叶片中____ （填“有”或“无”）大量淀粉产生．

如图所示，B、C、D、E、F，5个小球并排放置在光滑的水平面上，B、C、D、E，4个球质量相等，而F球质量小于B球质量，A球的质量等于F球质量．A球以速度v₀向B球运动，所发生的碰撞均为弹性碰撞，则碰撞之后（   ）