Don't worry. Your package ____ (keep) here until you come back, so enjoy shopping here.

八年级某班同学以“中国近现代外交”为主题创建了一个历史主页，下面是同学们为制作网页找到的图片和材料，其中有一些探究性问题需要你帮助解决。阅读下列材料：

材料一：

材料二： 清朝的西太后、北洋政府的袁世凯、国民党的蒋介石，哪一个不是跪倒在地上办外交的呢？                        ——周恩来

材料三：“周恩来并不打算改变任何一个坚持反共立场的领导人的态度，但是他改变了会议的航向。”                   ——美国记者评价周恩来

材料四： “我走完梯级时决心伸出我的手，一边向他走去。当我们的手相握时，一个时代结束了，另一个时代开始了。”         ——《尼克松回忆录》

请回答：

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。

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。

    I am writing to ask for whether you are able to do me a favor. I want to have a pen pal, hopefully a girl in the early twenties, and with interests similarly to mine. In my mind, he is someone interesting in traveling, swimming, and playing table tennis. Beside, it will be better for her to have a pet dog as I have been keeping one at home for some time. With such pen pal, I hope I can share with her my experiences in traveling, taking care of pets, or whichever we have in common. I believed I will improve my English by doing so and learning more about her country. I am looking forward to hearing from you soon.

下列变化过程不属于金属冶炼的是（　　）