假定英语课上老师要求同桌之间交换修改作文，请你修改你同桌写的以下作文。文中共有10处语言错误，每句中最多有两处。错误涉及一个单词的增加、删除或修改。

增加：在缺词处加一个漏字符号（∧），并在其下面写出该加的词。

删除：把多余的词用斜线( \ )划掉。

修改：在错的词下面划一横线，并在该词下面写出修改后的词。

注意：1）每处错误及修改均仅限一词；

2）只允许修改10处，多者（从11处起）不计分；

3）错误类型不涉及单词拼写。

    It is interested to visit another country, but sometimes there are some problem when we don't know the language very well. It may be difficult to communicate about the people there．We may not know how to use the telephone in the country where we are visiting. We must not know where to buy the things we need. In a strange country we may not know which to go to eat or what to order in a restaurant. It is not easy to decide how many money to tip（付小费）waiters or taxi drivers．When we are helpless, we may not know what to ask for help．After a short time later，however，we learn what to do and what to say. We learn to enjoy life in another country, and then we may be sorry leave both the place and people．

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如图，滑雪场有一坡角为20°的滑雪道，滑雪道的长AC为100米，则滑雪道的坡顶到坡底的竖直高度AB的长为（   ）