单项选择题
A.BA、IM、EM B.BA、EM、InternationalNursingIndex C.BA、IndextoDentalLiterature、InternationalNursingIndex D.IM、IndextoDentalLiterature、InternationalNursingIndex
A.digiatal(W)camera B.digiatal(N)camera C.digiatalANDcamera D.digiatalORcamera
A.一条记录 B.一篇文献 C.一个字段 D.一个文档