科学家发现人与黑猩猩的细胞色素C差异最小，与马的差异则大一些，而与果蝇、向日葵的差异更大．科学家研究的方法是（　　）

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阅读下列短文，根据短文内容填写表格。(每空限填一词)     

    Hi! Do you know the three children? They are in a happy family. Xiao Xue is a helpful girl. She is beautiful. She likes studying. She studies very hard. She gets up early and finishes her breakfast quickly .Then she rides her bike to school . Liu Xing is a little lazy. He gets up late and then washes his face, brushes his teeth in a hurry. Then he goes to the bus stop without breakfast. He usually plays basketball after school. In the evening, he seldom (很少)does homework. He goes to bed late. Xiao Yu is a lovely boy. He gets up very slowly and then he usually takes a shower(淋浴)at home before breakfast. After that, he goes to school in his father’s car. He likes watching TV in the evening.

已知x ，y满足条件$\left\{\begin{array}{c}\begin{array}{c}x-y+5\ge 0\\ x+y\ge 0\\ x\le 3\end{array}\\ \end{array}\right.$则z=$\frac{y-1}{x+3}$的最大值(     )

不等式组$\left\{\begin{array}{c}\begin{array}{c}{x}^2+y^2-2x-2y+1\ge 0\\ 0\le x\le 2\\ 1\le y\le 2\end{array}\\ x-y\le 0\end{array}\right.$表示的平面区域为D，区域D关于直线x-3y-3=0的对称区域为E，则区域D和E中距离最近的两点间距离为  （   ）