短文改错（共10小题；每小题1.5分，满分15分）
此题要求改正所给短文中的错误。对标有题号的每一行做出判断。如无错误，在该行右边的横线上划一个勾(V)；如果有错误（每行只有一个错误)，则按下列情况改正：
此行多一个词：把多余的词用斜线(／)划掉，在该行右边的横线上写出该词，并也用斜线划掉。
此行缺一个词：在缺词处加一个漏字符号(∧)，在该行右边的横线上写出该加的词。
此行错一个词：在错的词下划一横线，该行右边的横线上写出改正后的词。
注意：原行没有错的不要改。
Dear Mr. Donforth,
I’m writing to ask you come to our class for a visit. I’ve 76. __________
heard that you have been to Greece. In our Greece unit, we 77. __________
have been learning about it’s rich culture and long history. 78. __________
Since you have visited Greece several times, so I would like to 79. __________
know whether you have seen the old buildings here. We have 80. _________
learned a lot from the text book, but I believe you personal 81. __________
experience will be a lot better. Your knowledges of Greece can 82. __________
help the whole class. Could you share your experiences for 83. __________
us? It will be surely exciting and rewarding. I hoped that you 84. __________
think about my request and visit us as soon as possibly. 85. __________
．
，AC=
，由勾股定理R2=3+（3-R）2得R=2，