A few years ago, I took a sightseeing trip to Washington, DC. I saw many of our nation's treasures, and I also saw a lot of citizens on the street—unfortunate ones, like beggars and homeless folks.

    Standing outside the Ronald Reagan Center, I heard a voice ask. “Can you help me?” When I turned around, I saw an old blind woman with her hand extended. In a natural reflex (自然反射), I reached into my pocket, pulled out all of my loose change and placed it in her hand without even looking at her. I hated being disturbed by a beggar.

    But the blind woman smiled and said: “I don't want your money. I just need help finding the post office.” In an instant, I realized what I had done. I had acted with prejudice (偏见)---I had judged another person simply for what I thought she had to be.

    I hated what I saw in myself. This incident brought back my central belief. It reminded me that I believed in being humble (卑下的), even though I'd lost that belief for a moment.

    The thing I had forgotten about myself is that I am an immigrant (移民). I left Honduras and arrived in the US at the age of 15. I started my new life with two suitcases, my brother, my sister and a strong mother. Through the years, I have been a dish washer, roofer, mechanic, cashier and pizza delivery driver, among many other humble jobs. Eventually, I became a network engineer.

    In my own life, I have experienced many acts of prejudice. I remember a time at age 17---I was busboy (餐馆工), and I heard a father tell his little boy that if he did not do well in school, he would end up like me. I have also seen the same treatment of family and friends, so I know what it's like, and I should have known better.

    But now, living my American middle-class lifestyle, it is too easy to forget my past, to forget who I am and where I have been, and to lose sight of where I want to go. The blind woman cured me of my blindness. She reminded me of my belief in being humble, and to always keep my eyes and heart open.

    By the way, I helped that lady to the post office. And in writing this essay, I hope to thank her for the priceless lesson she gave me.

阅读下文，完成小题。
         ①蚯蚓，是一种环节动物，属质足纲寡毛目。
         ②蚯蚓生活在土壤中，以腐殖有机物和泥土为食。凡经它吞入而排出的泥土均成团烂结构，增强了土壤中的透气性和透水性，而且它排出的粪便是一种良好的有机肥料，富有硝酸盐和钾盐，可改变酸性或碱性土壤，使其变成中性，对农作物的生长极为有利。因此，自古以来，蚯蚓就被人们誉为“耕耘能手”和改良土壤的“功臣”。
         ③蚯蚓有惊人的消化系统，嗜粪肥和各种有机废物，除玻璃、塑料和金属外，其他垃圾它都“吃”，诸如蛋壳、香蕉皮、硬纸板或下水道中的污物，它都吃得津津有味，而且胃口也大得惊人。美国加利福尼亚州的一座蚯蚓养殖工厂，养殖了5亿条蚯蚓，每天吃掉垃圾200吨，并获得了大量的优质肥料。日本的一家工厂，每年处理木浆残渣需要40万美元，而购进125吨蚯蚓后，不仅及时清理了这些废料，还可以转而将蚯蚓粪便卖给附近的蔬菜农场，很快就收回了成本。所以，蚯蚓既是保护环境、处理城市有机废物的“主力军”，又是优质肥料的天然制造者。
         ④蚯蚓含有很高的蛋白质和维生素，因而成为现代化畜牧业、渔业的优良饲料、饵料。近年来，人们把蚯蚓烹调成营养丰富的佳肴。将来蚯蚓有可能成为人类摄食的主要动物蛋白。
         ⑤由此看来，蚯蚓确实是人类的挚友。由于蚯蚓神通广大，又具有分布广、适应性强、繁殖快、易管理等特点，很适合规模养殖利用，让它为人类造福。

如图所示，金属导轨MNC和PQD，MN与PQ平行且间距为L，所在平面与水平面夹角为α，N、Q连线与MN垂直，M、P间接有阻值为R的电阻；光滑直导轨NC和QD在同一水平面内，与NQ的夹角都为锐角θ。均匀金属棒ab和ef质量均为m，长均为L，ab棒初始位置在水平导轨上与NQ重合；ef棒垂直放在倾斜导轨上，与导轨间的动摩擦因数为μ（μ较小），由导轨上的小立柱1和2阻挡而静止。空间有方向竖直的匀强磁场（图中未画出）。两金属棒与导轨保持良好接触。不计所有导轨和ab棒的电阻，ef棒的阻值为R，最大静摩擦力与滑动摩擦力大小相等，忽略感应电流产生的磁场，重力加速度为g。

（1）若磁感应强度大小为B，给ab棒一个垂直于NQ、水平向右的速度v1，在水平导轨上沿运动方向滑行一段距离后停止，ef棒始终静止，求此过程ef棒上产生的热量；

（2）在（1）问过程中，ab棒滑行距离为d，求通过ab棒某横截面的电荷量；

（3）若ab棒以垂直于NQ的速度v2在水平导轨上向右匀速运动，并在NQ位置时取走小立柱1和2，且运动过程中ef棒始终静止。求此状态下最强磁场的磁感应强度及此磁场下ab棒运动的最大距离。

设m=${\left(2\frac{1}{4}\right)}^{\frac{1}{2}}$﹣（﹣9.6）⁰﹣${\left(3\frac{3}{8}\right)}^{-\frac{2}{3}}$+（1.5）^﹣2；n=log₃$\frac{\sqrt[4]{27}}{3}$+lg25+lg4+$7^{{\log }_{7}2}$．求m+n的值．