题目
1.没f(x)在 x=0 处连续,则f(x)在 x=0 处可导的充分条件为 ()-|||-(A) lim _(xarrow 0)dfrac (f(x)-f(-x))(2x) 存在,-|||-(B) lim _(xarrow 0)dfrac (f(ln (1+{x)^2)-f(0)}({x)^2} 存在,-|||-(C) lim _(xarrow -infty )dfrac (f(x)-f(0))(sqrt [3]{x)} 存在,-|||-(D) lim _(xarrow infty )xf(dfrac (1)(x)) 存在,

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