函数f(x)=log0.8(2x2﹣ax+3)在(﹣1,+∞)为减函数,则a的范围( )
A:(﹣5,﹣4
B:﹣5,﹣4
C:(﹣∞,﹣4)
D:(﹣∞,﹣4
质量为50 kg的乘客乘坐电梯从一层到四层,电梯自一层启动向上做匀加速运动,加速度的大小是1 m/s2,则电梯启动时地板对乘客的支持力为(g取10 m/s2)( )
—I will visit my grandparents in Beijing next month. Could you please tell me______?
—Oh, you may take the subway there.
“复数a+bia,b∈R为纯虚数”是“a=0”的( )