生石灰是石灰石煅烧而成CaO含量（）%左右。
A.50
B.80
C.30
D.55
参考答案：B
排序。
( ) I'd like some books.
( ) What book would you like?
( ) Can I help you?
( ) Here are some book on music.
( ) Some book on music.
( ) Sure.
大黄抗菌作用成分是（）、（）和（）。
