某患者单次静脉注射某药物10mg，已知t_1/2=4h，V=60L，请问给药30min后血药浓度是（）

A.0.153μg/ml

B.0.225μg／ml

C.0.301μg／ml

D.0.458μg／ml

E.0.610μg/ml

查询选修了课程号为'C2'的学生号和姓名，若用下列SQL的SELECT语句表达时，错误的是( )。

A．SELECT S#，SNAME FROM S WHERE S# =(SELECT SS# FROM SC WHERE C#='C2')

B．SELECT S#,SNAME FROM S，SC WHERE S#==SS# AND C#='C2'

C．SELECT S#，SNAME FROM S，SC WHERE S#=SS# AND C#='C2' ORDER BY S#

D．SELECT S#，SNAME FROM S WHERE S IN (SELECT SS## FROM SC WHERE C#='C2')