不少孩子晚上看电视时,喜欢把房间的灯都关上。他们感觉,这样电视屏幕显得亮、清晰。其实这对眼睛是不利的。电视屏幕与周围景物明暗程度的较大差别会增加眼睛的疲劳程度,所以晚上看电视时,不应把灯全部关上,而应让房间保持一定的亮度,比如开一盏3~8瓦的灯,但不要让光线直接照射在屏幕上。
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。
俗话说:“眼睛是心灵的窗户”,但我们该怎样保护好这“心灵的窗户”呢?在此,我教大家一些护眼的方法。
大家往往以为,只要放下课本或作业,就是休息眼睛了,比如看课外书、玩会儿电脑,甚至闭目养神。其实,这样只能是大脑得到休息,眼睛却依然“超负荷运转”。要想真正休息,最好的方法是看 5米以外的东西。许多人错误地认为,绿色对眼睛有好处,就是绿色本身对眼睛有什么好处,其实是指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,对眼睛也无益。
此外,我再给大家一些建议:
1. 切忌“目不转睛”,要经常眨眼,因为眨眼可减少眼球暴露于空气的时间,避免泪液蒸发。
2.不要吹太久的空调,并在座位附近放上茶水,用未增加周围的湿度。
3.多吃水果、蔬菜、粮食、鱼和鸡蛋。这样可以减轻眼睛干燥的程度。
4.保证睡眠的充足。
5.避免长时间用电脑。
来吧,让我们手拉手,摆脱眼睛的束缚!
看东西模糊了,有重影。眼睛发红,有刺痛、瘙痒感。眼睛干燥,有酸涩感。注意力不集中、头晕、肩酸,甚至头痛、恶心、呕吐。
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.
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