柴达木盆地的美称是( )
A:鱼米之乡
B:天府之国
C:聚宝盆
D:塞外江南
—Jack hasn't taken his piano lessons for a long time.
—He is considering _________ his piano course and spending more time on his study.
已知函数f(x)=ax3+x2(a∈R)在x=-43处取得极值.
(Ⅰ)确定a的值;
(Ⅱ)若g(x)=f(x)ex,讨论g(x)的单调性.
如图所示,电源电压为3V保持不变,两灯泡都标有“3V 0.9W”字样,要使两灯泡都能正常发光,以下说法正确的是( )