城市环境变化英语作文800字(热门20篇)

cars have created a lot of serious problems in our world. all the time, they are pumping huge amounts of waste gases into the atmosphere, causing disease and even death.

one possible solution is to design and develop clean cars and clean fuels. but it may take decades for the new models to completely replace the traditional ones.

another solution is to develop modern public transportation systems and restrict the use of private cars. if the price of petrol rises constantly and the public vehicles are efficient and convenient enough, most people will not drive private cars. on the whole, the elimination of air pollution needs the co-efforts from the government and the public. this problem will be solved only with the help of science and technology.

There is a saying, A girl changes fast in physical appearance from childhood to adulthood . I just had my eighteen years birthday. It s certain that I have grown much more beautiful now. My biggest change is not the appearance but in mind. I have become much more mature. I don t always think about going out to play instead of focusing my attention on study. I start considering my future. I try my best not to quarel with my parents as I know what they do is for me. I know I should filial my parents. What s more, I don t bully my younger sister and brother any more. I have changed a lot, because I have grown up.

俗话说， 女大十八变 。我刚刚过完我的十八岁生日。我肯定是变得更美了。我最大的改变不是在外貌上而是在思想上。我变得更加的成熟。我不再总是想着去玩而是把注意力放在学习上。我开始思考我的未来。我尽量不和父母吵架，因为我知道他们所做的都是为了我。我懂得了要孝顺父母。更重要的是，我不再欺负我的弟弟和妹妹了。我变了很多，因为我已经长大了。

[描写我的变化的英语作文

There is a saying,”A girl changes fast in physical appearance from childhood to adulthood”. I just had my eighteen years birthday. It’s certain that I have grown much more beautiful now.(laugh) My biggest change is not the appearance but in mind. I have become much more mature. I don’t always think about going out to play instead of focusing my attention on study. I start considering my future. I try my best not to quarel with my parents as I know what they do is for me. I know I should filial my parents. What’s more, I don’t bully my younger sister and brother any more. I have changed a lot, because I have grown up.

俗话说，“女大十八变“。我刚刚过完我的十八岁生日。我肯定是变得更美了。（笑）我最大的改变不是在外貌上而是在思想上。我变得更加的成熟。我不再总是想着去玩而是把注意力放在学习上。我开始思考我的未来。我尽量不和父母吵架，因为我知道他们所做的都是为了我。我懂得了要孝顺父母。更重要的是，我不再欺负我的弟弟和妹妹了。我变了很多，因为我已经长大了。

在很久很久以前,地球上鸟无花香,满山遍野看满了鲜花,动物们自由自在的生活,地球维持着生态平衡.

自从有了人类之后,地球就开始变了………..不再有从前的温和可亲,现在变得粗暴异常.这是怎么回事呢?

这全是应为人类!人类无休止的砍伐树木,造成动物快速灭绝.人类在世界各地建造化工厂,导致形成了酸雨.人类大量开采煤矿,导致空气中弥漫着的粉尘.破坏了生态平衡.

据不完全统计,有110种的亚种的哺乳动物以及139种的亚种的鸟类在地球上消失了.目前,世界上已有593种鸟、400多种兽、209种两栖爬行动物和20000多种高等植物濒于灭绝

酸雨在国外被称为“空中死神”,其潜在的危害主要表现在四个方面：(1)对水生系统的危害,会影响鱼类和其他生物群落,改变营养物和有毒物的循环,使有毒金属溶解到水中,并进入食物链,使物种减少和生产力下降.(2)对陆地生态系统的危害,重点表现在土壤和植物.对土壤的影响包括抑制有机物的分解和氮的固定,淋洗钙、镁、钾等营养元素,使土壤贫瘠化.对植物,酸雨损害新生的叶芽,影响其生长发育,导致森林生态系统退化.(3)对人体的影响.一是通过食物链使汞、铅等重金属进入人体,诱发癌症和老年痴呆；二是酸雾侵入肺部,诱发肺水肿或导致死亡；三是长期生活在含酸沉降物的环境中,诱使产生过多的氧化脂,导致动脉硬化、心肌梗塞等疾病概率增加.(4)对建筑物、机械和市政设施的腐蚀.

在煤矿生产过程中,破碎煤炭和岩石所产生的微小煤岩颗粒叫做煤矿粉尘.井下施工用的粉状材料飞扬起来也能成为煤矿粉尘的附加粉尘,如黄土、水泥、砂子和隔绝煤尘爆炸用的岩粉等.煤矿粉尘的主要危害,一方面是它的爆炸性,煤尘爆炸对破坏性很大,尤其是爆炸后产生的大量一氧化碳,能引起人的中毒死亡；另一方面,粉尘还能引起矿工患矽肺病和煤矽肺病.

大家一起行动起来,保护环境.让地球变回原来的样子吧!

Environmental problems are being more and more serious all over the world。

For example， cars have made the air unhealthy for people to breathe and

poisonous gas is given off by factories。 Trees on the hills have been cut down

and waste water is being poured continuously into rivers。Furthermore， wherever

we go today， we can find rubbish carelessly disposed。 Pollution is， in fact，

threatening our existence。

The earth is our home and we have the duty to take care of it for ourselves

and for our later generations。 Fortunately， more and more people have realized

these problems。 Measures have been taken to cope with these problems by the

government。 Laws have been passed to stop pollution。 I hope the problem will be

solved in the near future and our home will bee better and better。

Recently, it is very popular to live a low-carbon life.Living a low-carbon life is ofgreat importance to every one. First of all, it can protect the environment to a great extent. Second, it can save the limited natural resources and energy, and will leave a better world for our offspring.Third, it is a healthy lifestyle and will help mould a harmonious social atmosphere.

Therefore, how to create a low-carbon life is necessary for us to consider. To begin with, we should save the energy, such as the electricity, water and domestic gas. Second, when we go out we can walk or ride a bike instead of by car. Third, we should not use the plastic bags which are hard to break down. If so, we can live a low-carbon life and gain the happiness of it.

[保护环境英语优秀作文

From June1, 2008, shops and supermarkets are forbidden from offering free plastic bags to customers, according to a new law. A nation-wide campaign against plastic bags has been launched.

Nowadays, Chinese people use up to three billion plastic bags a day. While being very convenient to shoppers, plastic bags also cause serious white pollution” and waste resources.

Though the ban may cause some inconvenience to shoppers, it can help reduce the use of plastic bags when people have to pay for them. Besides, the ban, in away, can promote public awareness of environmental protection.

So I think it necessary to forbid shops and supermarkets from offering free plastic bags. When shopping, we can use cloth bags or baskets instead of plastic bags as we used to.

Dear John,

Im glad to hear from you. Now let me tell you something about our city. Nantong is trying to set up a national civilized city. We middle school students are also doing some things for it. We are all polite to our teachers. (In class, we listen careful to them./When we meet them, we always say hello to them./…)We also respect the old. For example, we help them cross the streets.

We are always ready to help each other.(When one has difficulty with his studies, others will help him at once./...)We often show our love to those in trouble. Last month, the students of my class donated money to the earthquake-hit areas.

Besides, we plant trees to protect the environment and make our city more beautiful.

Nantong is my hometown. I will do my best to turn Nantong into a civilized city.

Zhang Tong

Last weekend, I wanted to swim in the river that I usually wen in the childhood. When I went there, I was shock. The river is no longer like before. It was full of rubbish. It seemed that the rubbish is from the villagers themselves. In order to put the rubbish nearer, they put all of them into the river. Not only the water is not clean any more, the river also smelt bad. I real touched. Why human and the environment couldn’t live harmonious? Long time ago, they could get along with each other. Why not now? People have to stop their behavior to harm the environment. Otherwise, it would cause destruction to both sides.

上周末，我想去我小时候经常去的那条河里游泳。当我去那里的时候，我很震惊。河水再也不像以前那样了。河里面到处都是垃圾。似乎这些垃圾都是村民丢的。为了不走那么远丢垃圾，他们把垃圾都丢到河里了。水不仅仅不干净还会散发出臭味。我真的触动了。为什么人类和环境不能和谐地相处呢？很久以前，他们可以好好相处。为什么现在不可以了呢？人们必须停止他们伤害环境的行为。否则，最后会是两败俱伤。

记得两年前，我家山重后园还是一个垃圾乱倒、生活污水乱流、杂物乱放，甚至粪土乱堆的地方，环境很不好。

有一天听我爸说政府要对我们后园进行整治，说要建设新农村，要改善我们的生活条件，会建一个小公园。听到这个消息后，可把我乐坏啦，因为我想：如果爸爸的消息是真的，那等大人们把环境改善完后，我和我的好伙伴就可以在公园里尽情地嬉戏玩耍了。果然没过多久，来了很多人，接下来每天都有很多叔叔在忙着，场面相当的热闹，当时天气很热，可叔叔们不顾休息，个个干得热火朝天。渐渐地，两三个月过去了，我家后园的环境焕然一新。

经过那些叔叔们的整治，村里的垃圾堆不见啦，而且在固定的地方砌了放垃圾的槽位;附近的小溪流不再脏气熏人，变得清澈见底了，偶尔还能见到小鱼儿自由自在地游来游去呢;路边两旁的杂物也消失了，更让人欣慰的是种上一些花草，微风一吹，它们时不时会跟你点点头;最让感到恶心的是那些粪土，现在也消失得无影无踪了，听我爸说那些叔叔们在村里建成好几个公共卫生间，而且每天有专门的人进行打扫清洗。最最让我们小孩子高兴的是，我爸说过的那个公园也建成啦，听说县里一位领导给它取个名为：水云涧。水云涧环境相当地优美，有花有草有树，又有水，绿树悠悠，鸟语花香，那些叔叔们除了在水云涧公园种花种草外，还建起一座凉亭，摆上了很多石凳，甚至安放了一些健身运动器材，多好啊!现在每到傍晚，水云涧公园人群滚滚，不仅成为我们小孩子的乐园，也成为村里大人们休闲的场所。

在那里，我经常听大人们在说：还是咱党和政府的政策好呀，看看，这次村容的整治，使我们后园的环境全变了，我做梦都没想到会变得这么快，这么好呀!以后，我们一定要多多支持配合政府的政策，他们是为咱老百姓的生活着想呀!是呀!我是小孩子，虽然不是懂太多，但是村里环境的变化我可是亲眼目睹的，我心里也暗暗地高兴：感谢这次的村容整治，让我家乡环境变得如此美丽!

I believe the school environment protection are important because students need a quiet and pollution-free environment to study. What we need to do in order to maintain our clean and neat environment to our students? First, we will need to have giant garbage can around each corner. Second, we will need to have school policies regarding littering and spits on the ground, where students and teachers would be fine if they violated the school policies. Third, we also will need to have garbage cans in classrooms, school main entrance, back door, parking lots, basketball court, ect. Last, we will need to announce the school policies, so the students and teachers will need to follow. By doing all this, we can promise the clean and neat environment for our current and future students.

Nowdays,our enviroment is getting worse and worse,it definetely affects peoples lives,study and also work.On the other hand,our lives,work and production is polluting the enviroment in a very serious way.Here arises a question,how do we save our enviroment.

As far as i am concerned,firstly we need to stop the cutting dwon trees to save the natural circulation.While the air pollution is becoming one of the biggest concern for all the goverments,we need to pay more attention on the sewage from the factories.Lastly,we also need watch our own action,because the white pollution is almost everywhere around us.

Obviously,saving enviroment is every ones shoulder.We need to call on all the citizens to let them know the importance of saving our planet.

Environmental pollution and ecological destruction, have to the human social economic development and peoples normal life constitute a reality threat. As a modern citizen, care for the environment, advocate civilized, doubtless is our own morality and responsibility.

Therefore, we are proposing the people from changing the traditional behavior style and concept of value, dealing with the environmental problems in daily life, cultivate voluntarily protect the environment, the moral sentiment, starts from me from you, starts from now to start, cherish every drop, each tree, each piece of lawn, every piece of land, civilized, tree to be fresh, we agree, we become the most simple quality, form "protecting the environment, everyone duty" of the good society as a whole.

人类的科技发展迅速，但是环境的情况却不容乐观。人们为了利益大肆破坏环境，却不知这样只会加速人类的灭亡，所以保护环境很有必要。

保护环境是刻不容缓的，全球的森林面积正以每年460万公顷的速度减少，沙漠面积每年增多，雾霭越来越严重，全球变暖还有自然灾害的增多这都是大自然在给我们警示和惩罚，我们一定要重视起来，每个人心中要有环保意识，不要只局限于当下的利益，要从长远来看，人类只有一个地球，破环环境就是毁坏人类自己的家园，就是加速自己的灭亡。

保护环境不是个人的事而是人人都需要共同努力的事情，如吃完东西把垃圾自觉放进垃圾箱，并分好类，不随地吐痰大小便，节约水电等等这些小事，只要我们坚持每天作者为不足道的一点，一天一星期可能看不出来，但是一年十年呢这积累起来也是很客观的。不过，反之而行，不注疑这些细节的话，大自然就会百倍的报复我们，一句古话说的好”勿以恶小而为之，勿以善小而不为”。

保护环境不仅仅是保护人类居住的环境，我们同样要善待好动植物们，它们都是我们人类的好朋友，同样对我们来说也是至关重要的存在。大自然中有食物链，如果我们破坏了其中的一项或某几项，看似简单却不想这时环环相扣。大自然中，植物依赖动物，动物也依赖植物，我们也不外如是，一对山雀一天可以吃400多条虫子，这样就可以很好的保护树木庄稼，而鸟类大部分都是以昆虫为食，没有它们，就会害虫泛滥，严重影响我们的生活。而植物则会进行光合作用和蒸腾作用，为我们提供水和氧气，这都是我们生活的根本。

保护环境对于现在的我们来说不是一朝一夕就能一下子治好的，需要我们不断的，漫长的努力，对于政府来说要加大监管力度，严惩破坏环境的企业，对与国家来说就要不断的发展科技，开发新型能源减少污染，对于我们这些学生来说就要树立好环保意识并且还要大力的宣传。我相信，只要我们坚持这么做，在以后一定会见到一个美丽健康的地球。

[环境变化的作文800字

In general, there are two ways of traveling, private cars and public transportation. Chinese people should regard public transportation as their first traveling opinion.

一般来说,有两种旅游方式，私家车和公共交通工具。中国人应该把公共交通工具作为旅游的第一选择。

First, there are so many people living in this countries that make it so crowded. If each chinese people own a car, there will be far more traffic jams and accidents, which increase you impatience.

首先,这个国家住着很多人，使得它非常拥挤。如果每个中国人都拥有一辆私家车，将会有更多的交通堵塞和事故，这会让你变得更加的不耐烦。

Moreover, there will be far more pollution resulted from cars. Once a car started, it release huge amount of dirty gas and heat, which lead to great pollution and result in green house effect.

再者，由于私家车将会有更多的污染。一旦汽车起动,它释放大量的脏气和热量，这会导致很大的污染和温室效应。

All in all, Chinese people should take public transpotation into consideration first。

总之，中国人应该以公共交通工具为第一选择。

有人说：要是我出生在美国,我准是个英语天才.也有人说：如果李白是我的老师,也许我早就成诗人了.现实生活中,有些人总是抱怨环境不好,总是千方百计想换个环境.可是环境变了以后又怎么样呢?还不是一如既往.于是我要说,改变环境不如改变自己.

只有不时地更换鱼缸,金鱼才能越长越大；只有将狼放归山林,狼的智勇与矫健才能被激发出来.可见,环境对动物的影响力是巨大的,同样,环境对人的影响也不容忽视.正所谓“近朱者赤,近墨者黑”,一个好的环境往往对人有着潜移默化的影响.古代的孟母也深知环境的重要性,所以才有了“孟母三迁”的故事.

“天有不测风云”,环境不是一成不变的,你可以改变它一时,却无法改变它一世.所以,环境的改变只是暂时的,自我的改变才是永久的.燕子总是躲在他人的屋檐下避风躲雨,一旦屋塌檐倒,只能流离失所.舒适的屋檐的确给燕子带来了暂时的安全与温暖,可它的一生也只能在心惊胆战中度过.

环境,象征着生活中一切客观事物,改变环境并不能改变一切,更何况环境也不是轻而易举就能改变的,我们无法阻止青春的流逝,死亡的降临,也无法阻止日月更迭、自然巨变,因为它们都在以一种不变的规则来变化,就像设计好的程序一般.对此,我们也只能顺应和接受.这时候,改变自我往往是更明智的选择.鲁迅面对暂时无法改变的黑暗社会,毅然改变了自己的志向,弃医从文,希望通过改变人们的思想而改变社会环境；贝多芬面对无法改变的听力障碍,毅然改变了自己的作曲方式,嘴衔铁棒的他谱写出了不朽的《命运交响曲》,这是他人生的高潮,也是他生命的终章.

与改变环境相比,改变自己更能培养意志与毅力.历史上“秉烛苦读”的例子不是很多吗?这些古人没有去抱怨环境,努力适应环境.就在这种改变中,磨练了意志,培养了矢志不渝的精神.

人人都随着社会向前发展,人人都在改变,但很多情况下,改变环境确实不如改变自己.要知道,每一次改变,你的灵魂都上升了一个台阶,你就向辉煌又迈进了一步.要知道,现在你改变的是自己,而将来终有一天,你改变的是你的命运!

让我打开相册，会看见两张新旧不同的照片。旧的一张，背景是古朴的，幽深的庭院，隐约可见瓜棚架和盆盆花草，画面很恬静，很安详。新的一张，背景是雄伟高大的厂房和高耸的烟囱，画面整齐，气派。

旧的那一张是在我幼年时拍的，照片上的庭院就是我的家。我住在一个平平常常的古朴小镇上，镇上随处可见一丛丛花草及一株株高大的树，那里，是鸟儿的天堂，夏蝉鸣叫的歌台，鸟语花香，给沉静的小镇带来了无限乐趣。

在不大的庭院里，种着几藤苦瓜，瓜棚下高高低低地排列着盆盆花草，院内弥漫着芬芳的花香和清新的草气，闻着使人心醉。那碧绿的瓜叶和橙黄的苦瓜花黄绿相间，看着使人赏心悦目。晚上，月光洒下，有时依偎在奶奶柔软的怀抱里听着爷爷道来的娓娓动听的故事，真是其乐融融。这些，如果有一天当一切皆失的时候，对于我，对于所有镇上的人，意味着什么?

新的照片时我在少年时拍的，照片上的厂房就建在我家的庭院的旧址上。

几年前，当我从顽皮的儿童长成稍稍懂事的少年时，我是以新奇的目光看待一切的变化。这一排排的楼房和小镇的庭院相比，多么高大、气派。昔日的平房夷为平地，一栋栋厂房拔地而起;昔日的大树杳无踪影，耸立的是一座座令人目眩的烟囱。农家的炊烟与厂区的浓烟相比显得黯然失色，鸟儿的鸣声对于机器的轰鸣显得多么衰弱无力。一切都使我很激动。

但是，在机器轰鸣，烟囱冒烟的同时，人们变得忧郁不安起来。爷爷的身体变得更衰弱，再烟雾粉尘的掩埋下，他频繁地咳嗽，我再也听不到他给我讲故事的声音。对于这一切，对于我，对于这镇上的所有人，对现在的所有人，对于后代，又意味着什么?

我要拍一张新照片，还是在原来的地方，画面上雄伟的厂房披着绚丽的朝霞，高耸的烟囱飘出青烟，绿影婆娑，芳草霏霏，那浓密的绿叶盖住噪音，那芬芳的草地吸收的粉尘，空气中又弥漫着花香，绿林中又传出了鸟儿的婉鸣，夏蝉的高歌。

[我发现环境变化作文

在一片茂盛的丛林里住着许多小动物，它们每天自由地生活、歌唱，别提多快乐了。可日子一长，丛林里的垃圾越来越多、青草越来越少：小松鼠在树上边啃边扔下的松果核；小白兔到处啃青草，连草根都吃得一截不留；野猪随处大小便；老虎吃了一半的食物……时间一久，那些东西便发出了阵’阵恶臭，招引来无数的苍蝇和蚊子。动物们纷纷向环境保护协会提出了抗议。

为此，青蛙会长召集动物代表进行了一场有关如何改善生活环境的会议，青蛙会长坐在生椅子上慢悠悠地说：“朋友们，最近大家都反映丛林的生活环境很差，我经过调查发现问题还是在于大家，比如说野猪……”

“这不能怪我，我们一直以来都是随便找个地方解决大小便的。”青蛙会长的话还没说完，野猪就红着脸大声吼叫起来。

“可现在不行了，你们数量众多，每只都这样，对环境的污染太严重了！”小白兔们大声喊道。

“胡说，难道只是我们的错？猎狗也时常这样，凭什么只说我们？”野猪龇着牙，怒气冲冲地跳起来，“再说，你们这几只小东西，别以为自己长得可爱就可以到处啃草皮，丛林里的草皮越来越不像样了，不是你们干的，是谁？”

“野猪，你别冲动！”啄木鸟出来劝说。

“你！破鸟，待一边去！尖牙利嘴的，连树皮也不放过，你有什么资格发言。”野猪可能是急红了眼，破口大骂起来。

“啪！”会场突然安静了下来，原来是青蛙会长扔了一张大口罩在野猪的大嘴上，那是一张神奇的口罩，只要一捂到嘴上，就要过两个小时后才会自动脱落。

野猪涨红了脸，拼命地撕扯口罩，却怎么也扯不下来，只能气呼呼地坐着一言不发。

会议进行了很久，动物们总是相互指责，青蛙会长的神奇口罩飞了一张又一张，最后所有动物的嘴都被牢牢地捂了起来。会场再也没有吵闹声了。青蛙会长也累了，躺在椅子上睡着了。

最终会议没有取得任何进展，动物们仍然我行我素，丛林里的环境依旧一日不如一日。后来不知从哪一天开始，动物们都陆续搬离了那里。那片丛林成了一片垃圾场。

[环境污染变化的作文

Low-carbon life means a kind of lifestyle in which people do their best to reduce energy consumption and carbon dioxide emissions.

Then，how can we live a lowcarbon life?Firstly，we should recognize that the lowcarbon life is not only a kind of lifestyle but also a life attitude.Each of us is responsible for the greenhouse gases in our daily actions.To combat climate change we have to take the combined efforts of everyone on the planet.Secondly，we should develop good habits in our daily life.Paper cups are made from cutting forests.We should try not to use them because trees can absorb carbon dioxide and reduce greenhouse gases.Similarly，lights should be turned off when they are not used，which will greatly reduce electricity consumption.

In a word，small actions above can make a big difference.

家乡是花园，有着鲜花的芬芳；家乡是森林，有着绿树的清凉；家乡是田野，有着收获的希望；家乡是雪景，有着冰晶的闪亮。

回忆过去，家家户户都为了不愁吃，小院里满是瓜果蔬菜。一年四季，只要能种点什么，小院里就会满满的，瞧去，各种颜色掺杂交错，杂乱无章。好拥挤、好杂乱的小院。现在，各家都不怎么种蔬菜了，而是种花。一年四季，鲜花不断。春天，月季、玫瑰等竞相开放。夏天花儿更加繁盛，五颜六色。秋天，本该百花凋零，菊花却傲骨怒放。冬天，瑞雪纷飞，梅花却在枝头绽放。一年四季，芬芳不断。香啊，花园般美丽的家乡。

再想以前，村里村外都光秃秃的，几乎没有树。到了夏天，在外边聊天的大人都顺着墙边坐，小孩们大都躲在屋里扇扇子。屋里像蒸笼，屋外像热锅。而现在，房前屋后，街道两旁，村里村外，都种上了绿化树，虽说不像森林那样茂密，但也绿树成荫。夏天，大人们在树下乘凉，小孩们在树下嬉戏。茂密的树叶，送来了阵阵清凉。爽啊，森林般清凉的家乡。

回首以往，田野里种满了庄稼，密密麻麻的，有玉米、水稻、花生等。那时人们的种植技术还不是很高，虽然辛勤努力了，但收获的却不十分理想。那用一滴滴汗水浇灌出的庄稼，好像有意跟人们作对似的。现在呢，随着科学技术的普及，遍地都是绿色无公害作物，实现了机械化生产，省时又省力，农民的腰包越来越鼓，业余生活也丰富了。春天，水稻如碧绿的海洋，泛起阵阵波浪；秋天水稻垂下了头，大地一片金黄，真可谓是“春种满野皆碧绿，秋收遍地是黄金”。乐啊，田野般满是收获的家乡。

回首往事，垃圾拥有一片乐土——街道，任意呆在每个角落，有时还迎着风翩翩起舞，甚至在水里游泳，让人看了就想躲，真脏啊。现在呢，垃圾都有了自己的归宿——垃圾场，街道整洁了，铺上了水泥路，成为了一个耀眼的亮点。净啊，冰晶般闪耀的家乡。

家乡在不断的变化。在我心中，家乡如妙龄少女，越变越好看，我从心眼里热爱我的家乡

[家乡的环境变化作文800字