[听力原文] 11-15When we can see well．we do not think about our eyes very often．It is(11) only when we cannot seeperfectly that we come to see how important our eyes are.People who are nearsighted can only see things that(12) are very close to their eyes. Many people who doa lot of close work，(13) such as writing, reading and sewing,become nearsighted.They have to wear glasses(14) in order to see distant things clearly. (15) Peoplewho are farsighted suffer from just the oppsite problem,They can see things that are far away，but theyhave difficulty reading a book unless they hold it atarm’s length．If they want to do much reading，theymust get glasses，too． 13（）