假定英语课上老师要求同桌之间交换修改作文，请你修改你同桌的以下作文。文中共有10处语言错误，每句中最多有两处，每处错误仅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：在错的词下划一横线，并在该词下面写出修改后的词。
I went to Shanghai Expo on last week. At the gate I happened to meet some America tourists. I greeted him in English and then we began to chat. I got to know that they were college students travel in China. They were busy with taking pictures and were much impressed with the changes had taken place in the past few years. After which, we visited China Pavilion and had a good time. We exchanged our email address so that we could write to each other on the future. They thanked me again and again. I was very glad to have a chance to practising my oral English. on去掉
网友回答
(答案→)on去掉
解析：
【小题1】考查时间状语前介词的用法。last week前不能用介词。故去掉on。
【小题2】考查形容词作定语的用法。在这里要作定语，修饰tourists，必须用形容词，American是形容词，而America是名词，所以America 必须改成American。
【小题3】考查代词的用法。这里要用来代替some America tourists，是复数，所以要把him改成them。
【小题4】考查动词的适当形式。they were college students travel in China中的travel是用来做定语，要用现在分词，所以travel要改成travelling 。
【小题5】考查形容词词组。be busy doing sth.或be busy with sth.忙于做某事，所以要去掉with。
【小题6】考查定语从句中的关系代词。which/that had taken place in the past few years是一个定语从句，用来修饰changes。关系代词在句中做主语，指代物，用关系代词which或that。
【小题7】考查连词。在这里，是要用代词来代替前面句子所表达的内容，要用that，which一般只能在定语从句中代替先行词。所以which要变成that 。
【小题8】考查名词的单复数.我们的电子邮箱地址，应该用复数，所以address要变成addresses 。
【小题9】考查介词搭配问题。in the future在将来。是固定搭配。所以on要变成in。
【小题10】考查动词的适当形式。前面有动词不定式符号to，后面要用动词原形。所以practicing 要变成practice。