为使路面具备必须的抗疲劳强度、抗老化和变形累积的能力，它必须满足( )的要求。
A．强度和硬度B．耐久性C．稳定性D．表面平整度
参考答案：B
-The problem wasn't difficult for him,was it ?
-______. He should have been given a more difficult one. [ ]
A. No,it was
B. Yes,it was
C. Yes,it wasn't
D. No,it wasn't
窦房结内游走心律的心电图特征有（）
A.同一导联的P波形态稍有不同
B.P波在Ⅱ、Ⅲ、aVF导联倒置
C.P-R间期≥0.12秒
D.P-R间期不恒定
E.同一导联的P波有直立、低平、倒置等形态
