Dear friends,
Do you remember your first day at a new school or in a new area? How about the1when your family2 to a new state? Ugh! What about the feelings of being a stranger?
Then, with time, you find someone who likes 3you like.  Friends are great gifts in life. I have good friends too,  but not because they are completely(完全的)4 .Sometimes they talk too much; sometimes they need me a lot. I know I ask too much of them. I hope my friends, like my father,5about me a lot.
I once told my friends to give me all their love and be generous and gentle. I told my friends, in other words, to love me6I loved them.
They didn’t7 me at first, but then they became kinder. My love for them slowly made them learn to8 friends. They learned to love others and 9the idea that LOVE is part of life.
If we listen to and try to understand each other, love10.We should work on it, even if it’s hard at first. A true friend loves US at all times.
Your friend,
Jesus

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．