从洗油馏分中能提取哪些物质？
参考答案：
从洗油馏中能提取α-、β、甲基萘、苊、氧芴、芴、吡啶盐基、喹啉和异喹啉等。
—Someone is knocking at the door. Is it Ann?
—It _____ be her. She is giving a performance at the theatre now.
A．may
B．must
C．can’t
D．mustn’t
谷类的主要成分？
