Two thirds of the students have declining vision because of watching too much TV and playing too much computer games, which strains the eyes. A quarter of the students read books while lying down, or read books while walking, which is also not healthy for one's eyesight. A few of the students study under too intense light, or too dim light, which affects the vision as well. To protect our vision, it is essential that we develop healthy habits of studying, for example, we can relax and look at distant objects for minutes after studying for an hour or two.
最新问答: 解答英语试题Mr Smith likes (classical) music 括号部分提问_____ _____ "主动,是因为在乎;不再联系,是因为感到自己多余!"的英文翻译是什么? 氧气能跟什么发生化学反应?它具有什么性?通常做什么剂? 磁场的方向和磁极的方向有什么区别吗 已知f(x)=x-a/x^2+bx+1 (1)求a、b的值.(2)求f(x)的单调区间,并加以证明(3)求f(x)的值域 1、A man so difficult to _____ must be hard to ________. 一个自上了初中后至今未搞明白的问题. 我们要写 怎么写比较新颖点呢?- ____是教学理论和教学实践的中间环节,其目的是通过选择适当教学策略和教学媒体,规划教学活动顺序. 2009年甲国某企业向乙国出口M商品,假设单位M商品价格为10单位乙国货币.2010年甲国生产M商品的社会生产率提高了6 文言文中“持”和“度”的所有意思 已知关于x的方程3m-x=2分之x+3的解为2,求代数式2(-m)的平方-m+1的值 小红8点钟开始画一幅画,正好在时针与分针第三次垂直时完成,此时是几点几分? E-mail,as well as t 若椭圆的离心率e为(√5-1)/2,该类似椭圆具有的性质b*b=ac,则离心率为 这是我的路英文怎么说>? After I __(take) the medicine,it started taking effect and s 谦谦君子,卑以自牧.请问整句是何意义?出自何处何人? 问一道高考数学题2009陕西数学文 第8题在三角形 ABC中 M是 BC的中点 AM=1 点P在AM上 满足向量AP=2 小明家5月份用电250千瓦时,其中用“峰电”150千瓦时,用谷电100千瓦时.请计算他们家使用峰电电价