不健康原因的英语作文【一】
近视眼的机理
当人眼球在调节松弛状态下，来自5米以外的平行光线经眼的屈光系统屈折后，不能聚焦在视网膜上者称非正视眼，又称屈光不正。屈光不正分为近视、远视和散光三大类。所谓近视眼是眼在调节松弛状态下，平行光线经眼的屈光系统屈折后形成的焦点在视网膜之前，在视网膜上形成一个弥散光环，所以看远处目标模糊不清。从近视眼视网膜发出的光线为集合光线，其焦点位于眼球和无限远之间，称为近视眼的远点。如被看目标恰好位于近视眼的远点上，则可在视网膜上形成焦点，所以近视眼看近距离目标清晰。
近视眼的病因
近视眼按程度分为轻度(-3.0D以下，中度(-3.0D--6.0D，高度(-6.0D以上，近视眼的病因目前尚不完全了解，可能与下列因素有关。
1.遗传因素：据调查近视有一定遗传倾向，一般认为高度近视属常染色体隐性遗传，中低度近视属多基因遗传。
2.发育因素：婴幼儿时期眼球较小，常为生理性远视，随着年龄的增长，眼轴逐渐加长而趋向正视，如发育过度则形成近视。
3.外因：青少年学生与近距离工作者中近视眼较多，这表明，近视眼的发生和发展与近距离工作有密切关系，尤其是照明不足，阅读距离过近，阅读时间过久，字体不清或过小，以及姿势不良等都与近视的发生有关。?
4、轴性近视：是指眼轴较长而眼的屈光力正常，这是最常见的一种近视。常见为发育和遗传有关，不良的卫生习惯加速发展，如阅读时灯光照明不合理，坐姿不端正，距书本及工作目标太近，以及过度用眼等。
5、屈光性近视：是指眼轴正常但眼的屈光力增强。常见有：
A.角膜膨隆，圈袍角膜。
B.晶状体异常，球悬晶体，晶体位置倾斜。
C.睫状肌痉挛，引起晶体过度调节。
不健康原因的英语作文【二】
Smoking is a bad habit that does harm to smoker and others. Many kinds of diseases and cancers are caused by smoking, such as tracheitis, lung cancer and many other diseases. Recent years, there are tens of thousands of people dying of smoking. But there still are many people enjoying smoking, because they think smoking is a kind of fashion and smoking is so cool, especially among teenagers. In addition, smoking does harm to others as well. Second hand smoking has been recognized harmful to other people. Even worse, it may cause more damages. Therefore, people should remember that smoking is harmful to others and those people who smokes should give up smoking as soon as possible.
吸烟是个坏习惯，它对吸烟者和别人都有害。很多疾病和癌症是有吸烟引起的，比如说气管炎，肺癌还有很多其他疾病。近年来，成千上万的人死于吸烟。但是仍然有很多人喜欢吸烟，因为他们认为吸烟是一种时尚，很酷，特别是青少年。另外，吸烟也会对别人有害。二手烟是公认的对别人有害的。更糟糕的是，它会带来更多伤害。因此，人们应该牢记吸烟有害他人，那些吸烟的人应该尽可能戒烟。
不健康原因的英语作文【三】
the sun rises in the east and sets in the west, which is caused by the rotation of the earth as you all know. but have you ever thought of the effect of the earths rotation on man and can you imagine what would happen if the earth stopped rotating?
the radius of the earth is about 6,370 kilometres. it takes the earth 24 hours to rotate once. objects on the earths equator move with the earth at a speed of 460 metres per second, and the air close to the earths surface turns at the same speed. if the earth stopped rotating suddenly, the air would keep flowing eastward at a speed of 460 metres per second. the wind would be fourteen times as powerful as a hurricane. at the same time sea water would rush eastward at a speed of several hundred metres per second, which might do damages much greater than a seaquake would do. obviously, men could hardly stand such a catastrophe.
even if such a catastrophe would not happen, there would be a great temperature difference on the two hemispheres of the earth, and the four seasons of the year would no longer occur because a day and a night would be as long as a whole year instead of 24 hours. all this would greatly affect the life of human beings, imals and plants and that would cause worse results than anything imaginable.
不健康原因的英语作文【四】
Recently, there is a popular saying: the world is so large that I want to have a look! As more and more people travel around during their holidays, tourists have brought large sum of money to the local people.
However, too many tourists also bring some problems to the local life. The most serious problem is the pollution caused by the uncivilized tourists. It’s reported that there were thousands of tons of rubbish left after the flag-raising ceremony on Oct. 1st. The uncivilized tourists left their rubbish wherever they go, polluting the local environment. Another problem is the traffic jam caused by so many tourists.
Tourist can promote the economic development of the local areas, but the pollution caused by those uncivilized tourists has brought severe problems. The local tourist authority should set up relative laws to protect the environment of the local areas, and every tourist obey the laws and help to make the places of tourist more beautiful!
不健康原因的英语作文【五】
（一）图像在教学中的最大优势——形象性
图像具有非凡的表现力。课堂教学中有许多内容，用文字去表述会比较抽象，而用图像去表现时却十分形象。图像具有信息量大、现场感强、直观感强、容易记忆、便于再现等特点，能充分地激活课堂的教学气氛，给教学注入新的活力。它可以多方面、多角度，以不同的形式描述某一事物，提供直观的教学素材，克服文字与口头表达形象性弱的缺点，有助于学生观察能力、自学思维能力的培养。
（二）符合初中学生的认知心理
图像输入具有直观性、新颖性、多样性和趣味性，形象生动的图像，既能提高学习效率，又能集中学生注意力，提高教学效果。图像的`运用能最大限度地调动不同感官在学习中的作用，使学生确立鲜明的、完整的表象，把注意力集中到学习的对象上，从而产生强烈的学习***和运用语言来表达的***。这种强烈的求知欲正是学生学习知识技能必须具备的内驱动力。初中学生年龄小，心理不够成熟，认知较直观，注意力不容易长时间集中，形象思维比较突出，对感性的事物较容易理解，对理性的知识则不易理解，课堂教学活动只有形式多样化，才能吸引学生注意力，激发兴趣。在教学中通过生动的语言、实物、动作、图像等创设一定的、真实的、有趣的情景，进行丰富多彩的课堂组织活动，可以激发学生的学习兴趣，充分发挥学生的主观能动性，让学生在模仿中熟悉和感知语言知识。
总之，运用图像进行英语教学，突破了传统教学的局限，提供了丰富的声像并茂的语言内容，最接近语言实际的自然语境，能使学生在真切的语境中学习到活的语言，实现语言习得的目标。
