引起生物可遗传变异的原因有三个，即基因重组、基因突变和染色体变异。以下几种生物性状的产生，来源于同一种变异类型的是                     
①蝇的白眼                        ②豌豆的黄色皱粒、绿色圆粒  
③八倍体小黑麦的出现              ④人类的色盲  
⑤玉米的高茎皱形                  ⑥人类的镰刀型细胞贫血症

据日本新闻网报道，日本警察厅5月13日下午发表的最新统计显示，到当日下午3时为止，东日本大地震的死亡人数已经超过了1.5万人，另外还有9506人失踪．两者合计遇难者为2.5×10⁴（由四舍五入法得到的近似数）人，下列说法中正确的是（　　）

三个学校分别有1名、2名、3名学生获奖，这6名学生要排成一排合影，则同校学生相邻排列的概率是(    )

根据短文，选择正确答案。

    Mr. White looks out of his window. There is a boy at the there side of the street. The boy takes some bread out of a bag and begins eating it. There is a very thin dog in the street too.

    The boy says to it, “Come here, good dog. I'll give you some bread.” The dog is hungry and goes to the boy, but he does not give it any bread. He kicks the dog. It runs away.

    Then Mr. White comes out of his house and says to the boy, “I'll give you a shilling.”

    The boy is happy and says,“Yes”. “Come here,” Mr. White says. The boy goes to him, but Mr. White doesn't give him a shilling. He hits him with a stick.

    The boy cries and says, “Why do you hit me? I don't ask you for any money.” “No,” Mr. White says, “And the dog doesn't ask you for any bread, but you kick it.”

先配置溶质质量分数为10%的NaCl溶液50g，下列操作错误的是（　　）