We see with our eyes. If we have poor eyesight，it will be difficult to see everything clearly. So it's important to take good care of our eyes. It’s quite unbelievable that an eye ball is the same size as a table tennis ball. In fact the eye ball is like a kind of mirror. We should do eye exercises every day. We also need to have a rest after a long period of reading.
注释:
t) poor eyesight视力不好
2) the some size of与……同样大小
3) a long period of reading一段长的阅读时间