设立对照时,给与对照组与实验组外形相同的无任何作用的物质(如淀粉),这种对照方法称为()。
A.标准疗法对照
B.配对对照
C.潜在对照
D.安慰剂对照
E.实验对照
参考答案:D
The doctors in Beijing did all they could______ Shao Zhanwei, mayor of Hangzhou, but he still died of heart attack at the age of 58.
A.save
B.to save
C.saved
D.saving
ExdI表示矿用()电气设备。
A.本质安全型
B.增安型
C.隔爆型