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阅读短文,判断正误。

    A father and his young daughter get on a bus and sit down. The conductor(售票员)comes to them for their money. The father says, "I want one ticket.”Then he gives the conductor some money. The conductor looks at the girl, then he asks, "How old are you?" The father starts to speak. But the conductor stops him, and the girl says, "I am six years old at home, and four years old in buses and trains. Father tells me that.’’ The father's face turns red. He has to take some money out of his bag and gives it to the conductor. The conductor gives him one and a half (半) tickets.

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小华同学配制了一定浓度的盐水,帮妈妈筛选出饱满的种子,她想知道所配制出的盐水密度,就用天平和量筒来进行测量,具体步骤如下:

⑴把天平放在水平桌面上,将____移到标尺左端的零刻线处后,发现天平横梁左高右低,应将右侧的平衡螺母向____(选填“左”或“右”)调节,使天平平衡;

⑵用调节好的天平测量空烧杯的质最m1

⑶把配制好的盐水倒入量筒中,测量盐水体积V,如图甲所示;

⑷把量筒中的盐水全部倒入烧杯中,测量烧杯和盐水的总质量m2,如图乙所示.请根据图中数据,帮小华同学把下表填写完整:

空烧杯的质量m1/g

量筒中盐水的体积V/cm3

烧杯和盐水的总质量m2/g

盐水的密度ρ/(g·cm-3

30

 ____

____

____

⑸以上方法测出的盐水密度值比真实值____(选填“偏大”或“偏小”);

⑹小华同学发现混杂在种子中的小石块也同饱满的种子一起沉入了盐水底部,她想知道石块的密度有多大,就选了一块大小合适且与其材质相同的石块,巧妙利用图乙所示的天平状态,按以下的步骤测出了石块的密度.

①用细线栓着石块浸没在盐水中 (石块未接触烧杯底且盐水未溢出),天平读数增大了△m1

②将石块缓慢沉入烧杯底部,放开细线,天平读数又增大了△m2

③石块密度的表达式ρ(用△m1、△m2及盐水密度ρ表示)____