Earned value technique(EVT)can best be defined as ______ .

A) analysis of the value of the equipment that has been installed as of the date
B) analysis of the sum of the labor costs, which have been incurred on the project to date
C) a method of project performance measurement
D) a method of measuring the amount of money that has been spent to date

脉搏血氧饱和度仪的原理和使用，下述哪项不恰当（）

A.仪器包括光电感受器、微处理机和显示器三部分

B.基本原理是血红蛋白吸收光线的能力与其含氧浓度的相关性

C.如严重低氧，当氧饱和度低于70%时，其测定数据可能不准确

D.因肢体活动发生接触不良时也可能有误读

E.不论氧分压多高，SpO₂均能反映PaO₂的变化