下列物质不能使品红溶液褪色的是（ ）
A．氯水
B．次氯酸钠溶液
C．二氧化硫
D．氯化钙溶液
答案：D
补全对话，一空一词。
A: Hi ! My name is Jiang Shan. __1__ your name?
B: Julia. Nice to meet you.
A: Nice to meet you, __2__. What's this in English?
B: __3__ a book.
A: __4__ do you __5__ it?
B: B-O-O-K, book.
A: __6__ that a book, too?
B: __7__, it __8__. It's a picture.
A: Is this a pen?
B: __9__, __10__ is.
A: Your English is very good.
B: Thank you.
边际成本
