填一填．

通过合理的收入分配制度，把“蛋糕”分好，让全体人民共享改革发展的成果，逐步转变收入差距扩大的趋势。说明                                   
①保证居民收入在国民收入分配中占合理比重、劳动报酬在初次分配中占合理比重是实现社会公平的重要举措
②通过发展生产不断提高城乡居民收入
③让全体人民共享改革发展的成果，就要通过发展，做大社会财富这个“蛋糕”
④把“蛋糕”分好，就要求社会成员之间的收入差距不能过于悬殊，要求保证人们的基本生活需要

下列关于自然现象的解释，正确的是（　　）

电脑键盘上的字母为何不按顺序排列？请你来做一项统计，下面是一篇小短文，根据短文中字母a，b出现的机会完成后面提出的问题：

Two Trips

Jack brought a small plane and began to fly it． He soon became excited and made his plane all kinds of tricks．

Jack had a friend，named Tom． One day Jack said to him，“I will pick you up in my plane．““I will be glad to．'answered Tom． They went up，and Jack flew around for half an hour and did all kinds of tricks in the air． Then they came down． Tom was to be back safely，and said to Jack，“Well，Jack，thank you very much for those two trips in your plane．“Jack was very surprised and asked，“Two trips？““Yes，my first and my last．'an﹣swered Tom．

根据上文填表

出现字母的个数	100	150	200	250	300	350	400
出现字母a的频数
出现字母a的频率
出现字母b的频数
出现字母b的频率

如图是某细胞的部分结构示意图，有关叙述错误的是（　　）