加热时能溶于氢氧化钠水溶液的是( )
A.香豆素B.萜类C.甾体皂苷类D.四环三萜皂苷E.五环三萜皂苷
参考答案:A
解析: 香豆素类成分具有内酯环结构,能够溶于热的氢氧化钠溶液。
— Where has Tom gone?
— He was seen _____ football on the playground a few minutes ago. [ ]
A. playing
B. play
C. to be played
D. played
下列对胰腺癌诊断有价值的检查应为()。
A.上腹部增强CT
B.CA19-9
C.EUS+FNA
D.肝功能
E.MRI