一弹簧振子振动过程中的某段时间内其加速度数值越来越小，则在这段时间内，振子的位移越来越____，速度越来越____，其位置越来越____平衡位置，振子的速度方向与加速度方向____。

材料一：在正常人的血浆中，NaHCO₃的含量约为H₂CO₃含量的20倍．当血浆中的NaHCO₃含量减少时，会发生酸中毒；当血浆中的H₂CO₃含量减少时，则发生碱中毒．

材料二：在初生蝌蚪或幼小植物体内，当自由水的比例减小时，机体代谢强度降低；当自由水的比例增大时，机体代谢强度升高．

材料三：Mg²⁺是叶绿素分子必需的成分；Fe²⁺是血红蛋白的重要成分；碳酸钙是动物和人体的骨骼和牙齿的主要成分．

材料四：人体某些组织的含水量近似，但形态却不同．例如，心肌含水量约为79%而呈坚韧的状态，脑中含水量约为84%而呈溶胶状．

材料五：血液在血管中呈液态，当血液从血管中流出后则会凝固．

    I sat down at my desk and started writing an emotional letter of gratitude(感激). But1it came to actually placing the letter into the mailbox, I froze. I couldn't do it.

    The2was to an old teacher with whom I kept in3through Facebook comments(评论). For the past couple of weeks, her Facebook page had4me to live my life differently—for example, volunteering more.

    Her5efforts weren't huge—she wasn't building wells in Uganda or6 lepers(麻风病人)in India, but instead she was doing7, local good deeds, such as serving as an elementary school crossing guard. These were things that I could do, too. She made me8I could do the same at home. I felt I should let her9 how her example positively influenced my life. That was10I ended up handwriting the letter. But now here I was, standing before the mailbox,11to place the envelope inside. Why was this so hard to do? I thought I felt strange because it wasn't like she was my best friend. I just knew her.12, after thinking it over, I put the envelope in the mailbox at last.

    Weeks later I received a Facebook message from her. She was13a difficult time and my note meant14to her. She said she had no idea that she was making such a15to others. Not only did this letter make her happier,16her response to it increased my level of happiness as well. I decided to write a gratitude letter of17to someone each month. I've been doing this for two years now and it has changed my life greatly. I'm more likely to18out the goodness in others and I am continuously more thankful for this19life I'm living. Expressing gratitude is a great skill to20. Life is too short not to do it.