"Life is like walking in the snow", Gran_爱下问搜题

搜题请搜索小程序“爱下问搜题”

问题选择题

"Life is like walking in the snow", Granny used to say, "because every step [ ]

A. has shown

B. is showing

C. shows

D. showed

答案

答案：C

选择题

如图所示电路，两个灯泡完全相同，闭合开关，电压表示数是3V．关于电源电压和灯L₂两端的电压，下列说法正确的是（　　）

A．3V 3V

B．1.5V 3V

C．3V 1.5V

D．6V 3V

填空题

设y₁=e^x，y₂=e^x+e^2x，y₃=e^x+e^-x是二阶常系数非齐次微分方程y’’+Py’+qy=f(x)的三个特解，则该方程为______．