电流型变频器是将电流源的直流变换为交流的变频器,其直流回路滤波是()
A.电感;
B.电容;
C.阻容;
D.感容
参考答案:A
I'm sorry that I can not accept your ________ to attend your birthday party, Linda, because
I'm ________ to answer all the customers' letters tonight by my boss. [ ]
A. requirement; required
B. demand; requested
C. request; asked
D. request; required
用两种方法检查已确诊的肺癌患者 100名,甲法检出68名,乙法检出54名,甲乙两法一致的检出数为38名。欲比较两种方法的检出结果有无区别,其检验假设H0为
A.μ1=μ2B.μ2=0C.π1=π2D.b=cE.P1=P2