变应性血管炎诊断较困难的原因()。
A.无特异性临床表现及实验室检查所见
B.无特异性临床表现
C.本病为少见病
D.实验室检查无特异性
E.医生对本病认识不够
参考答案:A
—Who is the best friend of _____ at school?
—I think Helen is. We often help each other. [ ]
A. mine
B. his
C. yours
D. hers
电信营业服务规范的核心内容是“()”。