小学英语歌唱比赛视频通用20篇

导语：你的假期是怎么度过的呢?有什么有趣的事?以下是yuwenmi小编为大家整理的英语作文，欢迎阅读与借鉴，谢谢!

From the sixteenth of January to the seventh of February is our Winter Holiday. I think everybody did a lot of things in the Winter Holiday. But I didnt. Let you to listen to my story of Winter Holiday.

I spend a lot of time on the homework… Every day in my Winter Holiday，I always got up late. Then I listened to the tape，it was nine oclock. Then I ate breakfast and then I did my homework during the daytime!I‘m not very slow but the homework was too heavy!

Im unlucky on the playing too. I played firecracker but I hurt my finger with the fire. Im careless to kindle the firecracker，so Im very unlucky.

I still unlucky on my friends party. In the morning，I wanted to get up early but I woke up at 10：50. After ten minutes，the party would start! So I only eat a piece of bread then I go to my friend‘s

home!And I stay at his home for a long time when I came home. My mother and father were very angry and they scolded me!

Im worried and feel unlucky on my weigh. Last term，I was 48 kilogram but now I am 51 kilogram!I must to do banting!

But most important，I have gone to Shanghai Ocean Aquarium，I want to go there very much because I want to see the horse，the monkey…in the sea. Now Ive done it . It is a bright dot in my Winter Holiday.

参考译文：

我们的寒假放假时间是从一月十六号截至到二月七日。我想每个人在这期间，都会去做很多的事。但是我没有这样。下面就让我来给大家讲讲我的寒假发生的事吧。

我花了很长的时间来做作业…，在寒假这段时间里，我每天起的都很晚。然后呢，我听录音机(tape),转眼到九点了。之后，我吃完早饭再花一整天的时间去做作业!其实我做的并不慢，只是家庭作业布置的太多了!

我在玩耍方面也显得十分倒霉。在我玩爆竹的时候，伤着了我的手指。我手拿着放爆竹的时候，太不小心了，所以显得很是倒霉(杯具变成了餐具现在很流行的一个词，杯具餐具-作文地带)。

在我与朋友聚餐时也相当倒霉。早上，我是想着早点起，可是等我睡醒时已经是10：50.十分钟后，聚会就要开始!于是我只吃了块面包就径直向朋友家跑去!在朋友家呆了很长的时间后，我回到家，我爸爸妈妈很生气并且还大骂我一顿。

我很担心我的体重，上学期，我体重是48KG，但是现在我已经涨到51KG了!我必须减肥了!

但是更为重要的是，我已经去过了上海海洋水族馆，我非常期待去那，因为在那我可以看到马、猴子……还有大海。现在我实现这个愿望了。这也是我这个寒假唯一的一个亮点。

今天有活动课，我们正玩得开心呢!突然，班主任老师急匆匆地走进教室说：“同学们，今天活动课，我们要在办公室门前进行一次拔河比赛。大家一定要齐心协力，尽你们最大的努力，看胜利是否属于我们。”

“噢!太棒了，拔河了!”班里立刻炸开了锅。

同学们叫着，跳着，一溜烟似的跑到了办公室门前。体育老师已经等在那儿了，她说：“同学们，拔河啦!规则是这样的：先把大绳子的一头捆在几大根粗树根上，再把绳子给你们，你们从土里拔出一个根，再拔另一个根，直到拔完为止，明白吗?”原来这样啊。我们飞快地跳进挖好的土坑里，便开始“拔”了。

“一、二、三”，“一、二、三”······随着如雷般的口号声，同学们顺利地拔出了好几棵树根。就差最后一根了，可这一棵树根真把我们吓住了，它太粗壮了。“我们一定要努力把它拔出来。大家加油啊!”同学们一个个磨肩擦掌，攒住劲用力拔起来。可是这棵树根想跟我们开玩笑似的纹丝不动，同学们被激怒了，又发起了一次进攻。老师们也在一旁为我们打气。

“冲锋号令”又一次下了，同学们眉头紧锁，脸憋得通红，一个个使出吃奶的劲儿用力向后拉。“动了!”树根动了一下，又动了一下，紧接着被拔出了地面。“我们胜利了!”大家齐声欢呼。

同学们心满意足地回到教室里，一个个都兴奋异常。这场胜利真是来之不易，只有心往一处想，劲往一处使，齐心协力，团结奋进才能取得最终的胜利。这就是我们有趣的“拔河”大赛，你觉着好玩吗?

As we all realized that every one of us will fail during our life. Take me

for an example, I fail in my exam. In fact, failure always does appear, which

also means that failure is a daily occurrence, however, when facing the failure,

different people have different attitudes.

Some people hold the view that failure is the meaning whenever they could

not be successful. Thus, if meeting with failure, they will feel so nervous that

they have no idea what they are supposed to do. As time goes by, they become

more and more dispirited while eventually, they could do nothing well.

On the contrary, there are some people tending to believe another idea.

From their point of view, failure is outstanding due to the fact that it can

give them plenty of encouragement. Therefore, if facing failure, they will be

quite courageous and then try their best to beat it, finally, they make their

dream come true.

From my perspective, failure is neither an excellent thing nor an

appreciating thing. Sometimes, it is capable to offer us with encouragement,

however, it can also make us unconfident now and then. Thus, if encountering the

failure, never could we be scared. What we should do is to face it bravely and

never give up.

In summary, I wish when failure appears, each one of us could confront with

it bravely and beat it, if possible.

I was a shy girl and I never dared to make performance in the public, but

everything will have the exception. Last week, our English teacher gave us a

job. All students needed to make performance in group. I was chosen to be the

protagonist in my team. At first, I told them that I couldn’t make it, but they

believed that I was the suitable person. So I practised hard and tried to get

over my fear. It was my stage. I stood in front of my classmates. With my

teammates, I finished my job. I felt so cool and dared to face so many

people.

今天是四年级的校运会，比赛项目有：定点投篮、接力跑和拔河。我们班都取得了优异的成绩。其中，拔河比赛让我印象最深。

拔河比赛准备开始了，我们班第一场的对手是四(1)班。这次不会有悬念了。可是我又一想：不能骄傲呀，上次我们班的张逸荣力气很大，可这学期他没来，而其他班可能转来了一些力气大的。可是比赛了，裁判用洪亮的声音喊“一二三”“加油”“加油”每个班的拉拉队都叫了起来。我用尽全身力气，脸憋得红红的，拔了起来。对手的力气不小，我们班渐渐被拉了过去。我这时偷偷看了一眼拉拉队和老师，他们个个都拼命喊“加油”“加油”我听了，想：大家都为我们班出力，我一定要更加努力。这时，我大叫一声“啊—”随着这一声的爆发，顿时我感觉增加了无穷的力量。我把这股力量使了出来，渐渐地，我们把绳子拉到了我们班这边!“嘟”裁判吹响了哨子，说：“四(3)班赢了!”“耶!”我把绳子放下，看了看我的手，哇!都红了，不过我一定要坚持。最后，我们班击败了每一个对手，拿到了四年级拔河比赛的第一名。

啊!这场拔河比赛真是令我难忘呀!

为了提高我们的生活能力，学校开展了劳动小能手打比拼活动。这不，我们年级积极响应，通过十个老师的商议，我们比赛的项目是---包饺子。

比赛的前一周，老师就给我们安排了比赛用品：每组有一个人带本组用的饺子馅，一个人带案板，老师给我们准备饺子皮。上周二一上课，老师就把六张桌子竖着放在每组前面，然后把案板、饺子馅什么的放在上面。准备工作做好了，我们等待比赛开始。

“三、二、一，比赛开始！”一声令下，我们组李之行就以最快的速度在饺子皮最外围抹上一点水，然后用筷子夹着少得几乎没有的陷放到皮带正中间，最后快速地捏紧。我们组 的同学非常惊讶，因为他包的不是饺子而是面饼呀！同学们观赛时很激动，有的恨不得站起来观看这妙趣横生的比赛。

终于轮到我上场了。十秒、九秒……我的心越跳越快，越绷越紧，“开始！”我拿起皮，用妈妈准备的好工具---一把塑料小刀舀一下陷往皮上一抹。然后抹水，双手一捏，一个饺子就包好了。虽然我自认为包的很快，结果却并不令人满意，三分钟才包了八个。冯思特两分钟竟包了九个！下次努力吧。

老师把我们亲手包的二百多个饺子煮了，我们尝到了自己亲手包的香喷喷的饺子，高兴极了。

“加油”！“加油”！咦？这个声音是从哪里传来的？原来是“小桔灯作文培训班”在举行激烈的端乒乓球跑比赛呀。让我来说一说经过吧！

今天上午，在作文培训班里，老师为了培养同学们的协调能力和团队精神举行了一场激烈的端乒乓球跑比赛。老师一开始讲了比赛规则：每五人一组，每组同学只能用一只手拿球拍端球行走，另一只手和身体不能接触球拍，运球时不能挨到别的选手，球掉了就捡起球，在原地继续向前走。哪一组先走完，就是优胜者。老师规则还没讲完，同学们就已经开始摩拳擦掌，跃跃欲试。比赛开始了，同学们一个个地开始运球，一会儿就轮到我了，我信心百倍地接过球拍，小心翼翼地走着。一不留神，球突然掉了，在教室里乱跳乱串，好像在专门跟我作对。尽管有点手忙脚乱，但我还是迅速从地上捡起球……。

这时，在一旁观看的同学有的在座位上静静地坐着，眼睛在比赛的同学身上穿梭。有的拿着瓶子，嘴对着瓶口，大喊“加油”。还有的同学早已按捺不住心理的高兴，跳到比赛场地来呐喊助威。

“停”！随着老师一声令下，这紧张激烈的气氛一下子静止了。比赛结束了，我们组赢了！我们组的同学相互击掌，欢呼雀跃，另一组的同学们垂头丧气。通过这次比赛让我明白了：一个人的力量是不够的，只有大家团结协作，才能赢得胜利。

早上7：15，公共频道播出了于丹老师讲述的《中小学生人格教育》，准时坐在电视机前进行收看，感悟很多。

“真正爱孩子的老师和父母，不是教孩子怎样去躲避挫折，而是教会孩子在面对挫折时，怎样去修复生命。”这段话出自于于丹老师，简洁有力的表明了家长对孩子教育的重要性。而我们学生应该做的，就是要孝敬父母，用节目中的话来说，孝敬就是给父母一个好脸色看。

在学习方面，首先我们要有兴趣。照样还是用孔子的一句话：“知之者不如好之者，好之者不如乐之者。”生命乐在其中，在学习一种知识的同时才能完成自己的开发。要知道成绩不能代表一切，孩子应该因材施教，对孩子要进行多元化教育，充分发挥孩子自己的潜能，如果孩子都变成了一种模式，那学习岂不是太单调了。写到这，我不禁想起了中国式教育：“分分分，学生的命根；考考考，老师的法宝。”不知道老师在听完讲的这些以后，会不会改变教育方式，换换教育方法。

此外，于丹老师还通过讲一些小故事来阐述道理。让我记忆最深刻的是：一对兄弟俩，两人乘船一起到一个大城市卖瓷砖。结果在路上，因为一场大风暴，瓷砖全都被摔成了碎片。哥哥当即就哭得稀里哗啦，而弟弟则很冷静。去那个大城市考察一番后，发现那个城市里有很多地方在装修。于是，弟弟把瓷器碎片都彻底砸碎，变成一船的马赛克，卖了出去，结果赚了大钱。于丹老师的四岁的女儿都懂得哭是无能的表现，那我们为何还要在挫折面前只会哭呢？要是一遇到挫折就随之堕落，那是绝对不行的。

又返回到刚开始的地方去，于丹老师更关心的那个问题“今天的孩子快乐吗？”“一个孩子在很小的时候，能不能拥有快乐的生命，可能比他掌握多少知识更重要。什么是一种生命快乐呢？”显然，不是上很多很多的兴趣班，有很多很多的辅导课，有好多好多的课外题。这些课程，已经在无形之中给我们学生的心理上增添了重大的压力。所以才会出现，孩子们“不懂得珍惜生命”之说。

那么，最后总结一下。于丹老师此次的讲座，主要分为四项内容：第一：父母应怎样正确认识孩子，如何拟定正确合理的人生目标。第二：孩子不听话，爱发脾气，作为家长应如何让正确引导教育。第三：怎样教育孩子理解父母，尊敬老师，懂得感恩。第四：培养孩子抵抗挫折能力的重要意义。

总之，此讲座值得一看！

Dear Mr. Williams,

Thank you for your letter of congratulation on my exam results. I was very pleased to hear from you. The results were a great relief. I did much better than I thought I would.

We are having a celebration party on Saturday 22 May and we shall be pleased if you can come. It is a party for me, but my parents and some of their old friends are joining in, so you will find "real people" as well as teenagers to talk to.

The party starts at half past six- drinks, and a buffet supper later. You said in your letter that youve given up driving, so my father will meet you with the car at San Mateo station. Please let me know what time your train arrives.

There is a good train back to San Palo at 10:30 and well arrange transport for you to catch that. I hope that wont be too late for you. It would be a pity if you had to leave while the party was still in full swing.

I do hope that you will be able to come.

Yours sincerely,

Lily Chen

Every sportsman should have sportsmanship. When defeated, he should GREet his opponent and congratulate him. If he can＇t, on one will care to be his opponent because he lacks basic decorum and the spirit of a good sportsman. A true sportsman has a generous heart, admits to his loss and does not act with vexation. Learning to have sportsmanship is very important. It doesn＇t always matter whether one wins or not. What＇s even more important than results is what you have learned from each competition.

The game was scheduled to start at start at eight o’clock on Friday night. Long before that, people began to arrive at the gymnasium.

By seven-thirty the seats were almost filled. The school band was there; they wore yellow and black uniforms. They started to play at about a quarter to eight. Everybody stood up, and the people sang. The game was about to start. Two teams ran out to the floor. The referee blew his whistle, and the game started. A basketball game is divided into two halves, and each half is divided into two quarters.

There is a rest period between the halves. During the first five minutes of the second half, the score was tied. From then on, the game was very exciting. First one team made a basket, then the other. The people cheered, and everybody was wondering which team was going to win.

今年暑假的一天下午，我们全家人在家里进行了一次别开生面的书法比赛。一切准备就绪后，我清了清嗓子宣布：“本次写字比赛是由小动物来完成，人是幕后指挥，能让小动物写出一个字或画出一幅画为及格，谁最有创意谁就是赢家。”说完，我们都各自秘密准备了一番，然后我们三个人互相看看，都是一副胸有成竹的样子。

比赛开始了，妈妈首先登场，只见她在干净的地板上铺了一张大白纸，在纸上零零散散地撒了小米，又在一个浅盘子里倒上绿色的颜料水，她要干什么？我和爸爸对视着，心里直纳闷。妈妈却朝我们神秘一笑，然后拿出一只小鸡，在颜料盘里把小鸡的爪子蘸湿，放在白纸上。小鸡在纸上啄米，一会儿，纸上便“画”满了绿色的叶片。我和爸爸为妈妈的奇思妙想拍手叫绝，妈妈得意地说：“怎么样，这叫‘雪地翠竹图’。”就在妈妈为她的杰作陶醉时，小鸡一下子坐在了白纸上面，把颜料弄得模模糊糊，再也看不清了。妈妈沮丧极了。

爸爸出场了，要我和妈妈还有他一起下楼，我们三人来到了蚂蚁窝旁。只见爸爸用饼干屑在洞口拼了一个“胜”字，片刻之间，一群蚂蚁爬了上去，地上形成了一个黑黑的“胜”字，爸爸正兴高采烈地欣赏着自己的作品，眨眼间，地上已经一片空白，蚂蚁们把饼干屑运回了洞里，爸爸败了。

最后该我出场了，我吸取了爸爸的教训，心想：蚂蚁能把饼干屑搬走，我就给它来个搬不走的。我先用胶水在地上写了一个“奇”字，又在上面撒了白糖。蚂蚁哨兵一会儿就引来了一群同伴，立刻，地上形成了一个“奇”字，它们也想把糖搬走，可脚却被粘在胶水上了。

爸爸妈妈傻了眼，异口同声地说：“还是亮亮最有创意，我们认输。”

比赛结束了，不仅我们全家人收获了快乐，想必小鸡和小蚂蚁也感到了新奇、高兴吧！

[有趣的比赛小学生作文600字

星期一下午，我们学校举行了全校学生拔河比赛。学生们都站在操场上，每个年级的各班级之间进行比赛。

我们班对战三(4)班，第一场我们班赢，第二场三(4)班赢。第三场异常精彩，大家心中充满斗志。随着哨声响起，我们班同学就咬紧牙关，使出吃奶的劲往后拔，眼看我们班就要被拔过线了，只听“1、2、3加油，1、2、3加油……”我们班同学的身体渐渐向后倾斜，一步一步地往后退，三(4)班马上就要被拔输了，我们班又加把劲，只听一声哨响，三(4)班终于被拔过线了。

我们班喝彩着、欢呼着：“我们赢了，我们赢了……”。这次比赛让我们懂得了一个道理：团结就是力量。我们还要争取下一次比赛的胜利!

Is the beginning of the eight month, the weather suddenly cold, not for a long time, durian snow drop from the clouds. After a while, the snow is big, like someone with feather million pots from heaven.

The snowflakes are hexagonal, and the speed of falling is very fast. Soon, Linyi City snow, trees, houses, the earth seemed covered with snow, like covered with a white blanket, covered with white cotton. All of a sudden, the voice of a cloud aunt was heard from the sky, "Hey, hey! You have a little mischievous struggle, do not go down together, otherwise, it will be a disaster! Look, the cars are all skid and crawling like snail. Look at the river, the people did not go boating!"

I came to the Riverside Avenue station, enjoy the beauty of the Yihe River Trail in the woods. Snow sprint like Olympic athletes like Liu Xiang, rushed into the river, along the Yi River south to travel. Looking at it, the beauty of nature in the snow has come into my eyes, and it is in my heart. The original paved with red brick trail, has now been completely covered with thick snow, like a white carpet, step up soft, also creaked! Look at the Yellow alfalfa, has been formed by the snow "quilt" pressure to breathe out of breath. The bare trunk of the tree also fell on the snow, the wind blew and the little trees shook their bodies, and the snow babies were able to join the brothers on the ground. I raised my head and saw a lot of lovely little snowflakes in the sky rushing to meet my brother. Yes, how happy it is to have a family reunion. At this time, I thought of Taiwan. The dear motherland is a chicken mother lying in the nest. She has two babies, one is Hainan, and the other is Taiwan. Now, Taiwan slips out of the nest, and the mother and Hainan are anxious to come back to Taiwan...

I crouched down, with the hand group made a big snowball, at high altitude, it descends at full speed, open floor million lotus.

The snow has brought a lot of fun to the children.

The snow was neither fast nor slow underground, I left the snow Riverside Avenue, leaving a trail of footprints on the snow.

12 March 2006

Dear Sir,

I am highly disappointed in the proposed 2004-05 budget cuts to educa1ion. Taking away basic aid status and slashing our school budgets is a recipe for educational disaster in our school. The future lies with our children. They must have access to high quality educa1ion.

My husband and I have worked hard to be able to live in a school district that provides high quality education for our children. Cutting funding in districts like ours will have a negative impact on property values.

The school that my daughter attends is hardly wha1 I would describe as a "rich" school. Parents are asked to pay for books for all the classes, science supplies and for their students to participate in the performing arts among other items. If our school is to remain a world leader in technological development, cutting our school funds is the worst possible choice to make.

Education funds should not be diverted away from education.

Yours faithfully,

Tom Williams

今天早上，妈妈带着我赶往了英语风采大赛的比赛处。

是这样的，一个月前高老师让我和几个小伙伴一起去参加星光英语举办的一次比赛。

签到后，我一直非常紧张，因为我怕我会背错，或把歌唱走调。是妈妈一直陪着我，并对我说：“你是最棒的，不需要紧张，你一定会成功的。”我还看见了我的好朋友和周老师，她们都对着我微笑。这是对我多大的鼓励和支持啊!表演结束后评委老师对我说：“你的表现还不错。”这让我兴奋不已。

老师们，同学们，谢谢你们的支持。更要谢谢我的老妈，因为您辅导我写了自我介绍，一直陪着我练习。

Spring Festival is the most importantand popular festival in China．Before Spring Festival ，the people usually clean and decorate their houses．And they go to the Flower Fairs to buy some flowers．During Spring Festival ，the adults usually give lucky money to children．

People often get together and have a big meal．Some people eat dumpling for dinner．

I Play Guitar

I like playing guitar,so my father buys me a guitar for fun.It is very funny.Then my mother asks me to have guitar class.She thinks to learn more skill

is good for me.I start to have guitar class.It is really funny at first.But later on,I feel very tired.It is not easy to get improved.I want to giveup,but I insist at last.Now I can pay several songs.I feel proud of it.

我弹吉他

我喜欢弹吉他,所以我爸爸给我买一把吉他的乐趣。这是非常有趣的。然后我妈妈问我有吉他课。她认为学习更多的技能对我有好处。我开始上吉他课。这是非常有趣的。但是后来,我感觉非常疲劳。不容易得到改善。我想给最后,但我坚持。现在我可以支付一些歌曲。我感到自豪。

Yesterday was the ninth day of the World Cup. There was a football match between China and Brazil. We know Brazilian Team is the top one of the world. Though the players of the Chinese Team tried their best, they still lost the game. The result of the game was 4:0. I think they did better than the first game.I believe they can learn a lot from Brazilian Team.

I hope the team of China will be a strong team one day.

昨天是世界杯赛的第九天。中国队对巴西队。我们都知道巴西队是世界上最好的足球队。虽然中国队队员竭尽了全力，但是还是输了。比赛结果四比零。我觉得中国队表现比第一场要好多了。我相信，他们能从巴西队那里学到很多东西。

我希望中国足球队终有一天成为强队。

Yesterday evening the team of China played against the team of Brazil. The game started at 7: 30. It was an exciting game.Brazilian Team is the best one in the world. Everyone in the team of China tried his best, but the team of Brazil was too strong.Chinese Team couldn＇t stop them. They kicked four goals, and our team lost the game.

We hope the players in Chinese Team can make great progress, and it will be a strong team one day.

昨天晚上，中国足球对迎战巴西足球队。比赛在7：30开始。那是一场令人激动的比赛。巴西队是世界上最好的足球队，中国队的每个队员都尽了最大努力，但是巴西队太强大了。中国队根本抵御不住他们的进攻，最终以零比四输了这场比赛。

我们希望中国足球队队员能取得较大的进步，将来能成为一个强队。

同学们你们听过“抢橡皮”的游戏吗？今天，我在快乐魔方课堂上就玩了这个有趣的游戏。

首先介绍规则：一张桌子上放一块橡皮，老师请两个同学上来，听老师的口令做动作，比比谁的反应更快。比赛前两个同学一定要双手交叉放在胸前，如果老师说三、二、一、右手，你却出了左手，那你就输了，反之那你就赢了。比赛分成两组，如果参加比赛的人赢了，就可以奖5个大拇指，他所在那组的同学，也可以每人奖3个大拇指。如此有趣的游戏又能赚大拇指，所有的同学都跃跃欲试，迫不及待要参加。

比赛开始了，我们组派出了聪明伶俐的刘钰锦同学，他大步流星地走上台去，他和他的姐姐比赛，我们都忐忑不安，担心他会输，这样我们就得不到大拇指了。当老师说预备时，我们所有人的眼神都目不转睛地盯在了那块小小的橡皮上，三、二、一，右手，刘钰锦凭借他敏捷的动作快速地抢到了橡皮。顿时我们欢呼雀跃，一个个都开心的笑了，我们不停地为他加油打气，接下来的连续两次，都是他赢了。我们组最终获得了胜利。

“抢橡皮”游戏不仅要眼疾手快，还要团结一心。我们今天开心极了，这真是一堂有趣的游戏课啊！

一天，我和表哥去外面骑车玩，突然表哥说：“我们来一场自行车比赛”然后就急速冲去，我没办法，只好也冲去。

我们冲啊冲啊，冲到饭堂时，表哥突然停了下来，我趁此机会超过了表哥，并大喊：“我赢了！”，可是表哥却说："得坚持直到回到家为止才算胜利。"我没办法，只好继续比赛。我骑啊骑，但总超过了表哥又被他反超回来。最后奇迹发生了：我们骑到了一个斜坡，因为斜坡表哥速度变慢了。我没命地骑，终于骑过了表哥。这次他怎样也骑不过我了。我骑到了一个路段，然后发现表哥没有跟上来。开始加速起。骑到了一个交叉口。因为是红灯，所以很多车。因为我想赢，所以我不顾红灯冲了过去，当我冲过以后，表哥刚好骑过来，被挡在那里。我看到表哥被挡住了。心里高兴极了。便向家的方向冲到放车的地方。谁知表哥回来后居然说我耍赖闯红灯，不算赢。

好玩有趣的一天就这样结束了！

[自行车比赛小学生作文