①有一种公共卫生工作，需要在最短的期限内，把所有腐烂物质消灭干净。巴黎至今还没有解决可怕的垃圾问题，那集几百万人口的城市，倾其财力智力，都不能解决的，在那小小的村庄，却用不着花钱，甚至不用操心就办到了。

    ②大自然给田野创造了两种清洁工，没有什么能让这些清洁工厌烦、气馁。第一种清洁工包括苍蝇、埋葬虫、皮蠹、食尸虫类、阎虫科，它们被指派来解剖尸体。它们把尸体分割切碎，在胃里把死尸的残骸细细研磨之后再还给生命。

    ③一只鼹鼠被耕作农具划开了肚皮，已经发紫的内脏弄脏了田间小道； 一条躺在草地上的游蛇被过路的人踩死，而这个笨蛋还以为做了件大好事呢；一只还没长毛的雏鸟从窝里掉了下来，摔在托着它的大树脚下，可怜地变成了肉饼；还有成千上万的类似的残骸，出现在各个角落，分散在四处。如果没谁去清理它们，它们腐烂后散发的臭气就很有害。不过不要担心。只要哪儿出现一具显眼的尸体，小小的收尸工马上就赶到了。它们处理尸体，掏空肉质，把尸体吃得只剩下骨头，或者至少也会把尸体变成风干的木乃伊。不到一天，鼹鼠、游蛇、雏鸟，就都不见了，这环境卫生真令人满意。

    ④第二种清洁工，干起活儿来同样热情高涨。城市里用来减轻我们负担的氨气刺鼻的厕所，乡村里几乎见不到。当农民想一个人呆一会儿的时候，随便一堵矮墙，一排篱笆或一丛荆棘，就是他需要的避人场所。用不着多说，在这种无拘无束的场合，您会撞见什么。苔藓花、厚厚的青苔、一簇簇的长生草和其他美丽的东西，装点着久经风雨的石堆，吸引您走过去，来到看起来是一垛给葡萄培土的墙跟前。好家伙！在装饰得那么美丽的掩蔽所的墙脚一带，有一大滩可怕的东西！您拔腿便跑，什么苔藓、青苔、长生草，都吸引不了您。不过，您明天再来，就会看到那摊东西不见了，那个地方干干净净；因为，食粪虫已经到过这儿。

    ⑤这些掩埋工做的工作，对田野里的环境卫生意义重大。而我们，则是这种持之以恒的净化工作的主要受益者。但我们给这些忘我的工作者的，差不多就是轻蔑的一瞥，还用俗语给它们加上种种难听的名字。做好事的，背骂名，受歧视，挨石头砸，给脚跟踩。这好像成了一条规律。蟾蜍、蝙蝠、刺猬、猫头鹰，还有别的一些帮助我们的动物，都证明了这条规律。它们为我们做贡献，可要求我们的只是一点点儿宽容。

阅读下面短文，从短文后各题所给的四个选项(A、B、C、D)中，选出可以填入空白处的最佳选项。

    Smiling is the most desirable human behavior. We tend to overlook the power of smiling, 1 can work out many wonders and miracles.

    In my spare time in the State, I loved to take a walk around the small community where I lived.  2 I met on the way, they always gave me a friendly greeting accompanied with a nice smile as soon as our eyes had 3 . Spontaneously(本能地), I smiled back. This kind of smiling exchange represented the most  4 part of my jogging experience in the State.

    When it comes to doing business, my  5  is “I love to see my customers smile”. If a customer smiles when he sees you, it means he feels comfortable  6 with you. More importantly, it means he makes money. If he can make money, I get the business rolling.

    On a personal note, my daughter's giggle(傻笑) is just like  7  which warms my inside the same way  8  the sun warms my body. It can  9  away any clouds and unpleasant feelings.  10 I see her photo, her giggle  11  around my ears. The little reserved and controlled smile of my wife,  12 , reflects the beauty of a matured and well-learnt woman. It is so  13  in my eyes. It can sometimes really turn me on.

    Julia Robert's  14 is nothing but roaring like earthquake or volcano. It can overtake men and women alike. Americans may  15 in many other ways, but they all agree that Julia is America's sweetheart. Nobody can 16 her laughter plays a very good part in her acting. Once I tried some candy in a store, the owner asked me how sweet the candy is, I said sweeter than Julia Robert. Both of us  17 into a kind of Julia's laughter.

    Yes, laughter is something we can not do without. Otherwise, our life would be too gloomy.

    Smiling does not belong to human alone. Once I stayed at an American home  18  he had a little doggy by the name of Mini. Mini is a lovely pet. Every time we came home, she jumped up and down and insisted  19 giving me some lipping. When I held her gently and asked her to give me a little smile, she just  20  her mouth and half closed her eyes, looking like every inch of smiling. That left a deep impression on me.

    What I love Los Angles most is not only it is the place where it has sunshine most days in a year but also where most people smile!