若函数f(x)=x2-2|x|-m的零点有两个,则实数m的取值范围是[ ]
A.-1<m<0
B.m>0或m=-1
C.m>0或-1≤m<0
D.0<m<1
答案:B
简述小组工作的定义。
Do you think Beijing Opera is interesting or _______? [ ]
A. exciting
B. boring
C. moving
D. tiring