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，修改或删除。

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，并在该词下面写出改正后的词。

注意：1.每处错误及其修改均仅限一词；

2.只允许修改10处，多者（从第11处起）不计分。

Last Sunday I am about to leave the Green Lake Park when I met a foreign visitor whose seemed to be lost. I tried to help him but I found we had difficulty in understand each other because of my poor English. Just at that moment, tall young lady came to our help. He spoke very good English. With her help, the foreign visitor finally found the way but I learned some English as well. Before he left, the foreigner thanked to us for our kindness. I was very exciting that day. This experience have made me realize that English is real useful and worth learning. I will work hard at it from now on.

试述手拉葫芦（导链）使用要求？