若按2009年的移动电话增长率保持不变,预计到2010年年末全国移动电话用户数是多少?()
A.87034万户
B.87063万户
C.87107万户
D.87135万户
参考答案:C
已知函数f(x)=x3+ax2+bx+c,下列结论中错误的是( )
A.∃xα∈R,f(xα)=0
B.函数y=f(x)的图象是中心对称图形
C.若xα是f(x)的极小值点,则f(x)在区间(-∞,xα)单调递减
D.若xα是f(x)的极值点,则f′(xα)=0
To save class time, our teacher has ________ students do half of the exercise in class and complete the other half for homework.
A.us
B.we
C.our
D.ours