A:would have been unthinkable
B:would not be unthinkable
C:would be unthinkable
D:would not have been unthinkable
已知函数f(x)=2x且f(x)=g(x)+h(x),其中g(x)为奇函数,h(x)为偶函数,若不等式2a•g(x)+h(2x)≥0对任意x∈1,2恒成立,则实数a的取值范围是____
下列关于水的叙述,错误的是