小学4年级英语作文优秀20篇

假如我当英语小老师，我要充分利这短短的40分钟，培养同学们学习英语的兴趣，让他们以后能自觉学习。

假如我当英语小老师，我首先要请教我的老师，家长，并去书店或者上网查资料。

假如我当英语小老师，我要认真备课，把我知道的英语知识全部教给同学。

假如我当英语小老师，我不会让同学们感到累。同学们可以随便怎么坐，只要认真听课就行。

假如我当英语小老师，我不会让同学们觉得上课没有意思。我会组织一些有意义的活动，让同学们积极参加。

假如我当英语小老师，我会买一些小东西作为奖品奖励给认真的同学。

我上六年级了！步入六年级的教室，我不禁暗暗思忖：“我长大了吗？”这天吃中午饭，望着我即将与其身高相同的老妈发问：“妈，爸，我已经上六年级了，这算得上长大了吗？”爸妈笑着摇头说：“那可不一定。”我只好继续埋头吃饭。

在那一天，我才明白长大的道理。那天上午放学，我和两个同班同学李星月、江竹君一起步行回家。雾很大，在这个时候也丝毫没有减退的迹象，能看见的也只有前后10米左右。我们同学三人依旧蹦跳着，往家的方向前进。

路上的行人渐渐稀少。一个骑着摩托车的男人经过我们三个时，还回过头来瞅了瞅正在蹦跳行走的我们。突然，这个陌生的男人再次回来时在我们旁边一个急刹车，说了一声：“小朋友！”还未说完，我便一个转身，拼命往身后跑，江竹君和李星月也立即回过神来，往身后逃去。那个陌生男人眼见我们跑开了，只好骑着那辆摩托车，“突突突”地朝前骑走了。我们惊魂未定，立即朝家里快速赶路。

终于到家了！我和小伙伴们道了别，便冲了进去。我将这件事的来龙去脉仔细告诉了爸爸。爸爸听了，高兴而又意味深长地说：“海跃，你真的长大了！”

哦，原来长大并不意味着年龄的增长、身躯更加高大，而就是一种精神和道德的进步！的确，也只有有着自卫自保能力的人，才算就是长大了。

Whats friends? Do you have friends? I have many friends, so I always feel

happy. In the morning, some of my friends will go to school with me. We often

talk and laugh on the way to school. Sometimes we will stop to buy some snacks,

school things and other stuff. When I am in school, I always study with friends.

When I have something confusion, I will ask them to help. So do they. We help

each other. After class, we play together, and go to the shop to buy snacks.

They accompany me, so do I. I think this is friends.

“爱护地球吧!这是我们共同的家园，这是我们共同的母亲。” "Love to protect the earth! This is our common home, this is our common mother."

曾有人为“爱护地球珍惜资源。”举行过和演讲呼吁人类为了自己的生存拯救地球也曾有人为“爱护地球珍惜资源”献出自己仅有的一次生命，拯救地球地球。地球用以来树木帮我们造成;房用草原来哺育着我们。地球养育了我们我们应该怎样对待地球呢?长期以来，人们对地球索取的多，保护的少。为了眼前利益而滥伐森林、滥垦草原、滥捕野生动物、滥挖矿产等，这“四滥”的后果都是在破坏自己生存的家园!

历史的长河会永远记住，1998年那场灾难的洪水，长江两岸的大堤死守的百万军民，与洪水展开了生死搏斗。无情的洪水淹没的房子上坐着一个小女孩，那悲痛的一张小脸上显出一些孤单与可怜。裸露的田地，俏丽的建筑，可这些又有什么用呢?人们一次又一次的砍伐树木，使城市、村庄遭到了沙尘暴一次又一次的袭击。

这些都给人们的生命和财产带来巨大的损失，恶果都是我们人类自己造成的。20世纪五十年代，世界森林也遭到严重破坏，平均每分钟约有20公顷森林从地球消失。1970年至1990年的20年中，印度森林面积减少了40%，其后果是加剧了印度洪水和干旱。这些不仅仅是在迫害地球，而是在破坏整个人类。

同学们!这些种.种事情，难道还不能给我们教训与启示吗?

我们少年儿童是跨世纪的公民，21世纪的主人21世纪的地球属于我们，也属于我们子孙后代。为了人类社会的可持续发展，我们要让这的地球，有限的资源，既能满足我们这一代人生存与发展的需要。为了今天;为了明天;为了自己;为了子孙;让我们大家携起手来关心地球，做一些我们力所能及的事情，来爱护我们共同的母亲。

Ladies and gentlemen, I want to say something about trees. As we know now

trees are very important to human beings. First of all, they benefit our health.

They send out oxygen for us to breathe. We cant live without trees.Secondly,

trees can beautify our environment.

As trees are so important, we must do our best to protect them. We must

enforce the tree protection laws. We must plant as many trees as possible.Only

in this way can we live happily in the beautiful world.

My father doesnt talk much. Though he is not funny, he loves me very much.

Last week, he travelled for business and when he came home, he took out a box

and brought me a nice present. I was so happy. He always remembered to bring me

some surprises. It was a special notebook and I could use it to write

diaries.

去图书馆看书

The weather of today is very comfortable, though the weather forecast said

it is cloudy, but just a little bit rain, very cool.

今天非常炎热，一大早起床就感觉闷热的难受。吃完早饭妈妈让我陪同她去买菜我也没去。因为实在是太热了，感觉动一下手指头身上都在向外冒汗。

The weather forecast said it is cloudy, and friends about to play

basketball, but unfortunately, in the rain can play. Afternoon after the rain

stopped to help my mother to buy food supermarket. Generally bad mood today.

下午到市图书馆看了一下午的书。因为图书馆有空调可以吹，而且书也比家里的多太多了。顺便查了一下日全食的资料。

I have a beautiful room. Although my room is very small, I love it very much. Look, there is a bed near the window. I like sunshine so my bed is set near the window. In front of the bed, there is a desk on which is several series of books. What’s more, I have plastered my bedroom wall with photos of my family. The light in my bedroom is light pink because I like this color.

我有一件很漂亮的房间。虽然我的房间很小，但是我很喜欢它。看，靠近那里有一张床。我喜欢阳光所以我的床是安在窗户边的。床前有一张桌子，桌子上摆了几套书。我还把卧室的墙都用我们家人的照片挂满了。我卧室的灯是粉红色的，因为我喜欢这个颜色。

Do you like my bedroom? If you like, come here and have a look!

你喜欢我的卧室吗?如果你喜欢，来看看吧!

在当代这个物欲横流，权势金钱为主主宰的社会，我们更需要文明，更需要文明带来的幸福。 In a society where contemporary material desires, power and money dominate, we need civilization and the happiness brought by civilization.

文明在上世纪中叶十分盛行。那个年代，社会风气清明，政治气氛和谐，人们相互关系融洽，好人好事蔚然成风。雷锋的事迹被人传颂，雷锋的精神被人红颜。而现在，半个多世纪过去了，国家强盛，人民富裕，可文明道德精神却逐渐缺失。现在这个社会，我们需要的不再是物质，而是文明道德!

校园需要文明。正因为文明才有同学见到老师主动问好;才有同学见面相视一笑;才有同学在他人有难时伸出援助之手。正因为文明理念铭记于心，才没有人从楼上向下泼水，扔饭，才没有人穿拖鞋进学校，才没有人出口成“脏”。“文明”已成为了青春校园一道亮丽的风景线!在成长的路上，我们只有拥抱文明，才能更幸福的走下去!

社会需要文明。“90”后斗殴，求拍摄给特写并挑衅受害者发人深思;“丰县一女子裸体被打，跪地求饶，打人者死不放手”的视频让人看了触目惊心;更有不让座引来70老汉的一顿狂骂;翻拍剧遭网友犀利批评;看到小女孩被车轮碾过而无动于衷;老人跌倒在地无人搀扶;更有甚者为了金钱假药泛滥，食品假冒，知识贬值，尊严扫地等等。这些事件的发生不禁让人感叹：现在人们的爱心在哪里?人们的道德在哪里?人们的文明精神又在哪里?

当今社会，我们渴望雷锋精神的再次出现，我们期待更多像岳可一样的美德少年，像徐雪虹一样的好心同学，像郝帅一样的孝子，像吴菊萍一样的最美妈妈，像杨茂才一样的诚信之士文明之花处处盛开，校园美丽，社会和谐，世界更美好!

如果没有文明，北京奥运会怎能顺利举办?“世博会”如何在上海开展呢?欧洲杯又怎么会选择乌克兰和波兰?如果没有文明，中国华人与外国人又怎么和谐相处?国与国之间又怎么相互往来?如果没有文明，世界战争何时停止?国际矛盾如何化解?国际纠纷如何消除?可见，文明不仅影响校园、社会，更影响世界!世界需要文明，世界需要和平!

如果文明是一座桥梁，那么桥梁的另一端是人们和谐共进的社会;如果文明是一棵树，那么树上的果实是人们和睦相处的明天，如果文明是一阵春雨，那么雨后的彩虹便是人们美好的向往。

The math teacher of my class is a young man. His name is Jiang Shan. He is tall and fat. We call him the “Big Guy”. When he knows it, he isn’t angry and says it’s lovely. He is easy going and interesting. We can make jokes with him. But about our study, he is serious but patient. We can’t be sloppy on our study. When we have questions, we can ask him anytime. He is a good teacher.

"Pursuit of the perfect idol the same time, same time talented idols, the legendary weapons of China want to learn, everything is magic will be cool again." Christmas party in laughter came to a close, just like that. Recall JiYuTong they elaborate scene, in the mind... So, let us together with an endless again! This Christmas is precious, it is beautiful, but also we spent in primary school the last Christmas, meaningful!

In the afternoon, when we all walked into the classroom, having a unique style when everyone excited, when the classroom becomes hot, the "Christmas party" has officially kicked off.

We fight, itch to try. One funny show who is happy, sweet, make us all to my memory. We join together to sing the "inverse fight", "where dad", "I believe" and other songs; The forms of performance respectively, and the most to my favorite one show, is Wu Andi and Qiao Xinran acting funny sketch - many problems. This essay makes us burst into laughter, she classic lines to our delicious, relish!

Such as: Xu Zhao outcrop, audience friends must worry; Xu Zhao two outcrops, crosstalk from the impressive; Xu Zhao 3 outcrop, frighten to death a cow in the field. Xu Zhao four outcrop, the national peoples jump off a building. And learning is not outstanding, literature and art is not outstanding, lumbar shoulder dish outstanding, do not speak in class, the meeting is not speak, flat conductor yan. More online games such as study, dont dine. The college entrance examination examination of six or seven door, lack of a selective college door... Listen to the humorous language, how can not happy? ! And I am the "audience" also turned into "performer". Sang together with Wu Andi, Qiao Xinran and JiYuTong TimeZ "idol same time". Also became the last a finale performance!

翻译：

“追求完美的偶像万万岁，才华洋溢的偶像万万岁，十八般武艺每一样都要学，会变魔术又会耍炫。”圣诞联欢会就这样在欢声笑语中落下了帷幕。回想起冀宇童她们精心布置的场景，历历在目……那么，就让我们再在一起回味无穷吧!

这个圣诞节是珍贵的，是美丽的，更是我们在小学阶段度过的最后一个圣诞节，意义非凡!

下午，当我们每个人都走进这间别具一格的教室时，当每个人都激动万分时，当教室里变得热火朝天时，这个“圣诞联欢会”就正式拉开了帷幕。

大家摩拳擦掌，跃跃欲试。一个个搞笑、动听、令我们心情愉悦的节目都令我记忆犹新。我们共同演唱了《逆战》、《爸爸去哪儿》、《我相信》等歌曲;分别表演了形态各异的节目，而最令我喜爱的一个节目，便是吴安迪与乔欣然表演的搞笑小品——《问题不少》。这个小品令我们哄堂大笑，一句句经典台词令我们回味无穷，津津乐道!

如：徐钊一露头，观众朋友准发愁;徐钊二露头，相声从此没看头;徐钊三露头，吓死田间一头牛;徐钊四露头，全国人民齐跳楼。还有学习不突出，文艺不突出，腰肩盘突出，上课不发言，开会不发言，扁导体发严。更有网游如学习，千万不能偏科。高考中考六七门，缺一难进高校门……听着这些幽默的语言，怎能不欢乐?!

而我这位“观众”也变成了“表演者”。与吴安迪、乔欣然和冀宇童共同演唱了TimeZ的《偶像万万岁》。也成为了最后一个压轴表演!

Winter holiday is coming. I am so excited.

In this winter holiday, I am going to take a trip with my parents by plane.We are going to Beijing. Then, I am going to go ice skating there. I am going to see the snow. I will play with the snow. I am going to make a snowman with my sister. Then we are going to visit the Great wall. At last, we are going to go back home by plane.

That will be fun in the winter holiday! I can’t wait!

一、Hello, my name is Tom. I’m from JianXi. I’m 10 years old. I’m short and thin. I’m a student. I study in Class2, Grade 5 of primary school. I like English class very much. Because English class is so much fun. There are 4 people in my family. They are my mother, my father, my sister and me. I like hamburger and chicken very much. Do you like me?

二、Hello everyone,My name is xxx . I am from China, with a height of xx cm, and a weight of xx kg. ,I was born in xxxx xx xx, My favroite subject is xxx。My favorite month is February,My favorite season is spring , My favorite sprots is runningMy favorite food is hambuger,,My favorite housework is sweeping the floor, I want to be a computer engineer , You could ask me why , ha , because I like piaying computer !

三、Good morning (afternoon), teachers and students!

My name is JinYue. Beauty is my English name. Im ten years old. Im an active(活泼的) girl. I like singing 、dancing、drawing and playing Pingpang.Im a student of Class one Grade four from Affiliated Primary School of Hefei Pedagogical College.I like Chinese, Maths ,English and so on.I study very hard,I hope I can become a excellent student. I like making friends and wish to be friend with all of you.This is me. Please remember (记住)me, your good friend --JinYue. Thank you very much!

四、Hello, everyone. My name is JinYue. Beauty is my English name. Im ten years old. Im a student of Class one Grade four from Affiliated Primary School of Hefei Pedagogical College. I like singing 、dancing、drawing and playing Pingpang. I like English. I hope to become your good friends. Thank you very much!

五、Goodafternoon, teachers! Today, I`m very happy to make a speech(演讲) here. Now, let me introduce (介绍)myself. My name is ZhuRuijie. My English name is Molly. I`m 12. I come from Class1 Grade 6 of TongPu No.2 Primary School. I`m an active girl. I like playing basketball. Because I think it`s very interesting. I`d like to eat potatoes. They`re tasty(好吃的). My favourite colour is green. And I like math best. It`s fun. On the weekend(在周末), I like reading books in my room. I have a happy family. My father is tall and strong(强壮).My mother is hard-working(工作努力) and tall, too. My brother is smart.(漂亮) And I`m a good student. My dream(梦想) is to be a teacher, because I want to help the poor (贫穷的)children in the future(在将来). Thank you for listening! Please remember(记住) me!

时光一天天地流逝，如今的我，已经是一名五年级的学生了。但是小时候的事情仍然历历在目。以前因幼稚做出的趣事也经常引起我的遐想。

Time passes day by day, now I am a fifth grade student. But when I was a kid, I still remember it. I used to daydream about the funny things I made because of my childishness.

记得我上学前班的时候，有一天放学后，妈妈让我复习那天学习的知识。可是我很贪玩，不想复习，就说：“我都会了，没必要复习!”妈妈说：“既然你都会了，就给我出题吧!”我听了，顿时来了兴致。要知道，我的梦想就是当一名老师，因为当时我认为当老师就不用学习，还可以管着好多人，让别人写题。这次我的梦想能实现啦!

I remember when I was in preschool, one day after school, my mother asked me to review the knowledge I learned that day. But I am very playful, do not want to review, said: "I can, there is no need to review!" mother said: "since you can, give me the problem!" I listened, immediately came to the interest. You know, my dream is to be a teacher, because at that time I thought that when I was a teacher, I didn#39;t have to study, and I could manage many people and let others write questions. My dream can come true this time!

于是我一溜烟跑到屋子里，从抽屉里拿出一张纸，一本正经地写起来。没想到，不写不知道，一写竟然就上了瘾。出一张卷子已经不能满足我了，后来，我又给爸爸、爷爷、奶奶等人出题，到最后还为他们判成绩、排名次。可是他们总是做错题，我非常认真地帮他们改正，并且不厌其烦地为他们讲解，然后把卷子贴在墙上“展示”。每当他们偷懒不想做，我就会批评他们不爱学习。过了几天，我家墙上就贴满了

So I ran to the house, took a piece of paper out of the drawer, and wrote it seriously. I didn#39;t expect that if I didn#39;t write, I would become addicted. It#39;s not enough for me to produce a test paper. Later, I gave the questions to my father, grandfather, grandmother, etc. and at the end, I gave them scores and rankings. But they always make mistakes. I#39;m very serious to help them correct them, and I#39;m not tired of explaining them, and then paste the paper on the wall to "show". Whenever they are lazy and don#39;t want to do it, I will criticize them for not loving learning. After a few days, the walls of my house were covered

卷子，密得如同贴上了一层壁纸。每当家里有客人来，我都要洋洋得意地带他们“参观”贴满卷子的屋子。他们都夸我是一个负责人的“好老师”。我更得意了，又出了更多的卷子……

The paper is as close as a layer of wallpaper. Whenever there are guests at home, I will proudly take them to "visit" the room covered with papers. They all praised me as a "good teacher" in charge. I#39;m more proud, and I have more papers

现在我长大了，对小时候的事情有了深刻的理解。其实，他们是故意将题做错，为的是让我多练习。我还傻傻地把它当成一件神圣的事，现在想起来是多么的有趣。多次的出题和批改都是一种对知识的巩固。多亏了这件有趣的事，为我现在的学习打下了良好的基础。我现在终于明白了当一名老师不是一件简单的事，不但要知识渊博，而且还要极强的责任心和爱心。以后我还要更加努力学习，争取当一名真正的老师。

Now that I am older, I have a deep understanding of what happened when I was a child. In fact, they deliberately made mistakes in order to let me practice more. I also foolishly regard it as a sacred thing, and now it#39;s so interesting to remember. A lot of questions and comments are a kind of consolidation of knowledge. Thanks to this interesting thing, I have laid a good foundation for my study now. Now I finally know that being a teacher is not a simple thing, not only knowledgeable, but also a strong sense of responsibility and love. In the future, I will study harder and strive to be a real teacher.

New York is the first big city in America. It is the world’s commercial

center and there are many sites that attract people from all over the world to

take a visit. One of the famous sites is the Statue of Liberty. Everybody knows

this great site and it has become the symbol of New York.

The Statue of Liberty stands on an island of the New York City harbor. It

is the tallest building ever built. When people get there, they will see a woman

holding a torch of fire. In her feet, people can see the chains that are broken,

which means she gets away from the restrictions and chases for freedom. There is

a book on her right hand, which is the Declaration of Independence.

The complete name of this statue is Liberty Enlightening the World. It is

the present from French people to American people. The meaning of friendship and

freedom are shared by both countries. Today, the meaning of the Statue of

Liberty is shared by the world. People can feel the peace when they see this

image.

my name is u fangyan. you can call me betty. im a girl. im 13. im 154 centermeters tall.im in inqi primary school.im in class 1, grade 6.my classmates are very nice to me.we often help each other,and learn from each other. i have many hobbies.such as drawing,writing, singing .... i like playing badminton best.its good for my health.there are 3 people in my family. theyre my father,mother and me.we love each other.my phone number is 86889886. you can call me if you like .

自由，是我们小学生的向往，我当然也不例外，沉重的负担使我经常头疼。 Freedom, is the longing for our primary school students. Of course, I am no exception. The heavy burden causes me to have a headache often.

我多么想象天空的小鸟那样自由自在的翱翔，没有约束呀，可是那怎么可能呢?

就拿我来说吧，每天上学放学，星期六星期天还要上补习班，放学做完老师的作业后还要做家长布置的课外作业，又不能看课外书，漫画书，做完了作业还要看《奥数1000题解》，《英语练习册》等关于学习的书，说个你们不介意的话，我一般是在上洗手间大方便时才能尽兴偷看啊!哎!命真苦啊!

而我们家长还经常说我们生活在好的时代，有时我想想我们不知道好在哪里?如果考试考得不好，家长说，老师训;考得还行的话，日子还好过;在家里，天天听到的是家长的车轱辘话：要好好学习，不然以后日子苦，考不好学校，还浪费很多钱……在学校，天天听到的是老师的顺口溜：不学好，没人找，学不好，是没动脑……哦，mygod!我的耳朵已经起茧数尺也。

每次做作业时，我常常会情不自禁对着天空发呆，自言自语：我的做不完的作业啊!你何时你才能让我休啊?云啊，你多逍遥，可以云游四海，风啊，你好自在啊，随意便可飘洋过海……

俗语说得好，“考考考，学生的烦恼，分分分，学生的命根”!哦，本人在此偶尔偷闲小憩了，还有一吐为快了，心中的乌云也散了。这不，还得赶紧写作业去吧，争取进步，做个好学生才是硬道理啊!

朋友们，如果你们也有着同我一样的向往，那么也请你和我一样在自己的笔上或心中吐出来吧，心里会好受些哦!

寒假的一天

It was a very busy evening, I was doing my homework at my home. My father

was writing a composition in the study room. My mother was interested in

Shanghai opera. She was watching a Shanghai opera contest. The apartment was

very quiet. Suddenly the light went out. It was a blackout, but I liked it very

much. It came and I didnt have to do my homework. We went to the living room

very slowly.

After 5 minutes, we all sat in the sofa. It was a lucky, fortunate day. I

said that lets held a concert. My parents agreed with me. I took out some

candles and lighted up. We were singing, laughing and talking. We had a really

good time. But while I was singing, the light suddenly turned on. Oh, my God. My

father went back to his room went on writing.

My mother turned on the TV and said to me “Dear, do your homework!” I felt

very frustrated. I sat at the desk and thought I hated light. I hoped there

would be a blackout the ne_t day. I thought I would enjoy myself more and more.

I went into a dream.

自从人类生活在地球上时，人类就开始依赖大自然给予的恩赐，但是时间久之，人们也忘记节约与爱护。无知，贪婪的人们开始肆无忌惮的破坏生态环境。 Since humans live on the earth, humans have begun to rely on the gifts given by nature, but for a long time, people have forgotten to save and love.Ignorant, greedy people began to destroy the ecological environment unscrupulously.

水是生命之源!如果没有了水，人类将无法生存。我们要留心生活中那些浪费水资源的事情，要尽可能的节约用水。要知道一滴水是多么的重要。当你在浪费水时，有些缺水地区的人们正忍受焦渴，甚至有人被渴死。当你拥有水时你丝毫不珍惜，可当你没有水时你会怎样?

我们不仅要爱护水，还要保护环境，到了现代人们开始大量开发资源与能源。人们疯狂的开发资源时，不知不觉中伤害了地球母亲，我们把地球母亲弄得伤痕琳琳，却浑然不知。

虽然这些资源给我们带来了很多好处，但我们不能太贪心。因为这些资源是很难再生的，比如煤矿，它们是古代植物遗体堆积在湖泊、海湾、浅海等地方，经过很多年的复杂的转化才形成的一种具有可燃性的沉积岩。还有汽油……它们都是很难再生的。我们如果再不节约使用能源，资源总有一天会开发光的。

如果人们将所有的资源都开采完了，或是资源都枯竭了。我们应该怎么办?我们会怎么样?

为了我们的地球，请我们应尽可能的节约有限的资源。

让我们行动起来——为了地球的明天，为了我们的明天!

The Mid-Autumn Festival is a very important Chinese festival. It’s on lunar

fifth of August.

In the evening, we have a big dinner. Look, there is a lot of delicious

food on the table. We can drink a glass of juice. We stand beside the table and

we say, “Cheers, cheers, happy Mid-Autumn Festival!” We make a wish to each

other. At night, the moon is usually round and bright. It looks like a ball. We

can enjoy the moon. Moon cakes are the special food for this festival. We can

eat moon cakes, too. In the Mid-Autumn Festival, my parents and I are all very

happy and excited.

22 March 2006

Dear Ms. Reinhart,

I am terribly sorry that I failed to arrive at BLCU last Friday. I hope that this did not mess you up completely, although I know that you had already made some special arrangements for my visit with you parents and friends. I am very sorry about all that. I am sure you will be sympathetic, however, when I tell you that my father is dangerously ill in hospital, and that I found it impossible to leave for the visit when he is in this state.

My father was working very hard on his project on protecting the environment. I know the project has come to a very important stage. He and his assistants did not take regular rest for three weeks. Last night, my father had a heart attack and was soon sent to the hospital. The doctor said my father was in a very serious situation, and, he might need an operation.

24 hours have passed. Nothing has changed. I have to stay at the hospital. I will let you know if there is any good news.

I am sorry again and look forward to seeing you soon.

Yours sincerely,

Tom Williams