I will call you up _______I get to Beijing. [ ]
A. as
B. since
C. though
D. as soon as
答案:D
已知混凝土的三轴应力状态为三向受压,应力比为:σ1:σ2:σ3=-1.0:-0.3:-0.15。试问下列各项中在三轴受压状态下混凝土抗压强度的提高系数何项正确
A.2.3 B.1.8 C.2.0 D.1.4
283频点的上行中心频率是(),下行中心频率是().