As earlier mentioned, ensure that your screen is at least 20 inches from your face. But while you focus on getting work done, beating a level on your game, or catching with suspense in your TV show, take your eyes off the screen for a moment. Do this every 20 minutes. ...
The Sun's angular diameter is measured to be 1920 inches. The distance D of the Sun from the Earth is 1.496 x 10^{11} m. What is the diameter of the Sun? If Earth be one half of its present distance from the Sun, by how many days will the present on...
题目The weather.It's always a talking-point in Britain.Why is that?Is it something strange about British people?Well it's nice to think that a lot of British people are eccentric(古怪),I mean,the place is famous for it.But really,it's the weather that's the ...