苷经酸水解后有机溶剂层的薄层色谱可检识（）
A．糖的种类
B．苷元的种类
C．苷的分子量
D．单糖间连接位置
E．苷键的构型
参考答案：B
Mary, you don't have to wear a pink dress today. In this sentence, " don't have to" means . [ ]
A. wouldn't
B. can't
C. needn't
D. needn't to
I can't figure out ____ you didn't call Ted back that day. [ ]
A. why it was that
B. it was why that
C. why was it that
D. that it was why
