区别甾体皂苷元C25位构型，可根据IR光谱中的()作为依据
A．A带＞B带
B．B带＞C带
C．C带＞D带
D．D带＞A带
E．A带＞C带
参考答案：B
his work these days，he hash’t _____ when to pay a visit to his parents·
A．Bent On：decided on
B．Worried about；turned on
C．Faced with；taken on
D．Devoting to；focused on
按工程建设标准内容划分的是( )。
A．国家标准
B．施工及验收标准
C．技术标准
D．强制性标准
