下列有关空气各成分的说法正确的是（　　）

   I am an English girl. My name is Mary. I’m twelve. My dad and mom are English teachers. I have a brother（哥哥）. His name is Tom and he is thirteen years old. We are in China now. We are in Beijing No. 4 Junior High School. Tom is in Class 4, Grade 7 and I am in Class 9, Grade 7. I have a dog. My dog looks strong. It has a big mouth and two big black ears. We have many(许多) Chinese friends here. They are good.

国际货币基金组织（IMF）在美东时间9月30日宣布，人民币10月1日正式加入IMF的                （SDR）货币篮子。IMF总裁拉加德发表声明称，“货币篮子扩容对于IMF、中国和国际货币体系来说，都是历史性里程碑。”（     ）