柯柏反应比色法测定炔雌醇含量的具体方法是
A.对照品对比法B.百分吸收系数法C.高低浓度对比法D.主成分自身对照法E.比移值(Rf值)法
参考答案:A
混合静脉血氧饱和度是使用何种导管监测()
A.外周静脉管道
B.中心静脉导管
C.肺动脉导管
D.三腔静脉导管
E.手指氧饱和度
It's said the police have started an investigation,________are being kept secret . [ ]
A. of which details
B. and the details of which
C. the details of it
D. the details of which