以下有关地应力来源的的说法,不正确的是()
A.上覆岩层的自重
B.地下水的压力
C.地质构造作用
D.岩土体开挖引起
参考答案:D
把电阻R1=4Ω,R2=8Ω的两个串联后接入电源为U的电路中,如图所示,闭合开关,测得R1两端电压U1=12V,求电源电压是多少V?
I will ring you up as soon as Jenny ________ back tomorrow. [ ]
A. come
B. came
C. comes
D. will come