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：在缺词处加一个漏词符号（/\)，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（一），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(从第11处起)不计分。
During the last summer holiday, my parents and I paid visit to my grandparents by train. There was a large number of people and the train was crowded, but everyone helped those who had lots of baggages and behaved politely. Along the way, we chatted happily and enjoyed beautifully views. At first, we saw one hill after other. Then which came into view were fields with green crops. In a six-hour trip, we arrived at my grandparents; house. Ti red as I felt, but I was happy to see my grandparents, whom I haven't seen for a long time. It was really an excited trip because it was the first time that I had taken such a long-distance train.
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N2O4（正反应为放热反应）。将该烧瓶放在热水中，对现象的描述正确的是
(g) 
2NH3(g) 达平衡的标志是
