计算：
-22÷（-1）3×（-5）。
解：-20
设a，b是方程x2+x-2013的两个实数根，则a2+2a+b的值为（ ）
A．2011
B．2012
C．2013
D．2014
A few of the young trees in Tangsa can be cut each year for firewood.The rest ________ to grow even taller.
A．left
B．will left
C．is left
D．are left
