每隔1小时休息一下双眼,不要持续操作。持续使用电脑时,要经常眨眨眼睛,防止眼睛干涩。眼睛距离35厘米大的屏幕不应少于60厘米,距离38厘米大的屏幕不应少于70厘米。屏幕应放在略低于视平线的位置。将屏幕的亮度与清晰度调整到适当水平,以眼睛感到舒适为准。要经常擦拭屏幕。屏幕过脏会使图像模糊,造成眼睛疲劳。
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.
Today smoking is a widespread habit ali over the world. Not only the old, the youth, but also middle school students have been engaged in smoking. Many of them think that smoking is a smart symbol.
However, smoking is harmful to one's health. It contributes a lot of lung cancer, from which many people have died in the past years. It can also cause many other diseases. In a word, if you smoke, you do have a much greater chance of losing your health. Furthermore, scientific research shows that smoking is not only harmful to smokers themselves, but also a threat to public health, especially to women and children. Therefore, many countries have made laws forbidding smokers to smoke m public places such as cinemas, stations, hospitals, and so on Giveup smoking! If you don't smoke, don't start. Give upsmoking for the sake of your health, for the sake of your family, and for the sake of the whole world.
当今吸烟是一个世界范围内的习惯。不仅是老人,青年,而且中学生都吸烟。他们中的许多人认为吸烟是一种潇洒的象征。
然而,吸烟有害人的健康。它会引起肺癌,其中许多人在过去的一年都死去了。它还可以造成许多其他疾病。总之,如果你吸烟,你有更大的机会失去你的健康。此外,科学研究显示,吸烟不仅对吸烟者有害,而且对公众健康构成威胁,尤其是对妇女和儿童。因此,许多国家都制定了法律禁止吸烟如电影院,车站,医院等公共场所禁止吸烟,如果你不抽烟,不要开始。戒烟吧,为了你的健康,为了你的家庭,和世界。
地震时的应急防护原则 震时就近躲避,震后迅速撤离到安全的地方是应急防护的较好方法。所谓就近躲避,就是因地制宜地根据不同的情况作出不同的对策。。地震一旦发生,首先要保持清醒、冷静的头脑,及时判别震动状况,千万不可在慌乱中跳楼,这一点极为重要。其次,可躲避在坚实的家具下,或墙角处,亦可转移到承重墙较多、开间小的厨房、厕所去暂避一时。因为这些地方结合力强,尤其是管道经过处理,具有较好的支撑力,抗震系数较大。地震时,门框会因变形而打不开,所以在防震期间,最好不要关门。夜间地震时,要争分夺秒向安全地方转移,不要因寻找物品和穿衣而耽误时间,如有可能,要立即拉断电源,关闭煤气,熄灭明火。照明最好用手电筒,不要用火柴、蜡烛等明火
总之,震时可根据建筑物布局和室内状况,审时度势,寻找安全空间和通道进行躲避,减少伤亡。在学校中,地震时要在比较坚固、安全的房屋里,可以躲避在课桌下、讲台旁、教学楼内开水间、有管道支撑的房间里,决不可乱跑或跳楼。地震时,在街上行走时如何避震?地震发生时,高层建筑物的玻璃碎片和大楼外侧混凝土碎块、以及广告招牌,马口铁板、霓红灯架等,可能掉下伤人,因此在街上走时,最好将身边的皮包或柔软的'物品顶在头上,无物品时也可用手护在头上,尽可能作好自我防御的准备,要镇静,应该迅速离开电线杆和围墙,跑向比较开阔的地区躲避。
一旦遇难,要尽量改善自己所处的环境,稳定下来,设法脱险。设法避开身体上方不结实的倒塌物、悬挂物或其他危险物;搬开身边可移动的碎砖瓦等杂物,扩大活动空间。注意,搬不动时千万不要勉强,防止周围杂物进一步倒塌;设法用砖石、木棍等支撑残垣断壁,以防余震时再被埋压;不要随便动用室内设施,包括电源、水源等,也不要使用明火;闻到煤气及有毒异味后灰尘太大时,设法用湿衣物捂住口鼻;不要乱叫,保持体力,用敲击声求救。
如果你正在影剧院、体育馆等处遇到地震时,要沉着冷静,特别是 当场内断电时,不要乱喊乱叫,更不得乱挤乱拥,应就地蹲下或躲在排椅下,注意避开吊灯、电扇等悬挂物,用皮包等物保护头部,等地震过后,听从工作人员指挥,有组织地撤离。
地震时,你正在商场、书店、展览馆等处,应选择结实的柜台、商品(如低矮家具等)或柱子边,以及内墙角处就地蹲下,用手或其它东西护头,避开玻璃门窗和玻璃橱窗,也可在通道中蹲下,等待地震平息,有秩序地撤离出去。
熙仁专家提醒:孩子们往往以为,只要放下课本或作业就是休息眼睛了,比如玩会儿电脑,看看课外书,甚至闭目养会儿神。其实,这样只能使大脑得到休息,眼睛却依然处于疲劳工作状态。要想真正休息眼睛,最有效的方法就是看5米以外的`东西。在学校时,应到教室外活动10分钟;在家,则应到阳台或窗前向外眺望10分钟。
绿色对眼睛有好处,并不是指绿色本身对眼睛有什么好处,而是说远眺大自然的景物可缓解眼睛的疲劳状态。如果看33厘米以内的东西,即使是绿色的,对眼睛也没有益处。
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