以甲醇为原料的一款新型手机电池，其反应原理为：2CH₃OH＋3X＋4NaOH=2Na₂CO₃＋6H₂O，其中X的化学式为(　　)。

阅读下文，回答问题。

合欢树

       十岁那年，我在一次作文比赛中得了第一。母亲那时候还年轻，急着跟我说她自己，说她小时候的作文作得还要好。老师甚至不相信那么好的文章会是她写的。“我那时可能还不到十岁呢。”我听得很扫兴，故意笑：“可能?什么叫可能还不到?”她就解释，我装作根本不再注意她，把她气得够呛。不过我承认她聪明，承认她是世界上长得最好看的女的。她正给自己做一条蓝地白花的裙子。

       二十岁，我的两条腿残废了。为了我的腿，母亲的头上开始有了白发。尽管医院已明说我的病目前没办法治，但母亲不死心，她到处找大夫，打听偏方，花钱买来些稀奇古怪的药，让我服用，让我洗、敷、熏、炙。“别浪费时间啦!根本没用!”我说。我一心只想着写小说，仿佛那东西能把残疾人救出困境。可母亲仍不放弃，直到最后一回我的胯上被熏成烫伤，这对于瘫痪病人实在太悬了。后来母亲发现我在写小说，她跟我说：“那就好好写吧。”我听出来，她对治好我的腿也终于绝望，但又抱了新的希望。“你小时候的作文不是得过第一?”她提醒我说。她到处去给我借书。顶着雨或冒了雪推我去看电影，像过去给我找大夫、打听偏方一样锲而不舍。

       三十岁时，我发表了第一篇小说，母亲却已不在人世。过了几年，我的另一篇小说又侥幸获奖，母亲已经离开我整整七年。

       获奖之后，登门采访的记者就多，大家都好心好意，认为我不容易。但是我只准备了一套话，说来说去就觉得心烦。我摇着车躲出去，坐在小公园安静的树林里，想，母亲为什么早早地走了呢?迷迷糊糊中，我似乎听见回答：“她心里太苦了，老天爷可怜她，就召她回去了。”这让我心里得到一点安慰，睁开眼睛，风正在树林里吹过。

       几年前，老街坊们就提醒过我：“到小院儿去看看吧，你妈妈种的那棵合欢树今年开花了!”我听了心里一阵抖。还说，我家原来住的房子里现在住了小两口，刚生了个儿子，孩子不哭不闹，光是瞪着眼睛看窗户上的树影儿。

       我没料到那棵树还活着。那年，母亲到劳动局去给我找工作，回来时在路边挖了一棵刚出土的小苗，以为是含羞草，种在花盆里长起来，竟是一棵合欢树。母亲从来喜欢那些东西，但当时心思全在别处。第二年合欢树没有发芽，母亲叹息了一回，还不舍得扔掉，依然让它长在花盆里。第三年，合欢树却又长出叶子，而且茂盛了。母亲高兴了很多天，以为那是个好兆头，常去侍弄它，不敢再大意。又过一年，她把合欢树移出盆，栽在窗前的地上。再过一年，母亲去世，我们搬离了同母亲住过的那个小院儿，悲痛弄得把那棵小树忘记了。

       与其在外边瞎逛，我想，不如就去看着那棵树吧。来到老院子，老街坊们还是那么欢迎我，东屋倒茶，西屋点烟，送到我眼前。大伙都不知道我获奖的事，也许知道，但不觉得那很重要；还是都问我的腿，问我是否有了正式工作。我问起那棵合欢树。大伙说，年年都开花，长到房高了。但我再难看见它了，因为老院里扩建了小厨房什么的，过道窄，摇车进不到里面的小院儿。我挺后悔前两年没有自己摇车进去看看。

       我告别了老街坊，摇着车在街上慢慢走，不急着回家。人有时候只想独自静静地呆一会。悲伤也成享受。

       有一天那个孩子长大了，会想起童年的事，会想起那些晃动的树影儿，会想起他自己的妈妈。他会跑去看看那棵树。但他不会知道那棵树是谁种的，是怎么种的。

下列电气设备中利用电磁感应现象原理工作的是（   ）

用一根与毛皮摩擦过的橡胶棒靠近一轻质小球，发现两者互相排斥，由此可鉴定（  ）

阅读短文, 从每题所给选项中选出可以填入空白处的最佳选项。

    Once upon a time, a little fish lived in a pond. But she wanted to go to the forest. The pond was deep, and high banks keep it from the view of the forest. Wanting to see the forest, the fish would jump out of water now and then, reaching 1 over the pond with the strength of her tail. It seemed to her that, with a little more effort, she could fly, but unfortunately each time she would fall right back into the 2.

    The fish's mother—a big fish with kind eyes would 3, “What would you want the forest for? We fish must live in water, and that is the way it is.”

    The fish would answer, “I want to go to the forest and that is my 4. And it must come true.”

    So she went to the little fairy(仙子) who had been friends with her for her whole life and pleaded(恳求), “Oh little fairy! I have been living in the water all the time. Now I am 5 my small world. I want to see those big trees covered with beautiful flowers, leaves and fruits. I want to meet 6 and animals.”

    To make her friend happy, the little fairy swung her little wand(魔杖). The rain started falling on the earth, and a few days later, the forest around the pond was covered with water,

    7 the small pond into a lake. The fish swam to the forest. How 8 it was! The fish was very excited because her dream would come true soon.

    “Hello,” the fish said to the flowers and the trees. She 9 on and saw animals sitting on fallen trees which were sticking out of the water. But as soon as she swam closer to the trees, she saw that all the animals were very sad. “We are without 10. The water has flooded the whole forest,” the animals told the fish 11. All this made the fish very unhappy.

    “I am 12 with this rain but my friends—trees and animals are quite unhappy. Oh little fairy! Please 13 the rain. I will go back to my pond. I will be more pleased when trees, animals and birds are happy,” pleaded the fish. The water began to 14 , and the animals were very glad and ran off, and the fish 15 to the pond and she was happier than ever before.

    The art of happiness is to serve all. To be really happy, we must think not only of how we can help ourselves, but how we can help others.