Three ___________ are playing football over there.[ ]
A. childs
B. children
C. childrens
答案:B
函数f(x)的定义域为R,f(-2)=2013,对任意x∈R,都有f′(x)<2x成立,则不等式f(x)>x2+2009的解集为( )
A.(-2,2)
B.(-2,+∞)
C.(-∞,-2)
D.(-∞,+∞)
建筑基坑降水中采用回灌,回灌井与降水井的距离不宜小于()m;回灌井宜进入稳定水面不小于()m。()
A.3.0;1.0
B.6.0;1.0
C.3.0;1.5
D.6.0;1.5