Look, it's a toy car.

为了测定不同泡制天数泡菜中亚硝酸盐的含量，某同学设计了一个实验，实验材料、试剂及用具包括：刻度移液管、比色管、不同浓度的亚硝酸钠标准溶液、亚硝酸盐的显色剂、不同泡制天数的泡菜滤液等．回答相关问题：

（1）请完善下列实验步骤．

①样品管的制备：用刻度移液管分别吸取一定量的，加到不同的比色管中，然后在各个比色管中加入等量的显色剂进行显色，得到样品管．

②标准管的制备：用____ 和显色剂制成颜色深浅不同的系列标准管．

③将每个____ 分别与系列标准管进行比较，找出与样品管颜色深浅____ 的标准管，该管中亚硝酸钠含量即代表样品管中的亚硝酸盐含量，记录各样品管亚硝酸盐的含量．

（2）泡菜制作过程中产酸的细菌主要是____ （填“醋酸杆菌”或“乳酸菌”）．

（3）如图表示的是泡菜中____ 趋势．

    A rich man loved his little boy very much. He wanted 1  him happy all the time. So he gave him everything that he could buy with   2 . But the little boy was still  3  .Where he went, he always wore a frown(皱眉). And he always wished for something he did not have. The rich man didn't know   4  to make his son happy.
    One day, a magician(魔术师) came and said to him, “I can make your son happy and  5  his frowns into smiles, but you must pay me a great price   6 telling him the secret.”
   “All right,” said the man, “No matter what you ask for, I  7  you.”The magician took the boy into a secret room. He wrote something on a piece of paper, and then gave it to the boy. There were some words on the paper, “Do one  8  thing for someone every day.” The boy followed the  9   and became one of the happiest boys.
    I think only those who are always thinking about   10  can be truly happy.

4个8相加的和为____。