The old lady’s hand shook frequently.She explained to her doctor this shaking had begun half a year before,and ,only because of this,she had been forced to give up her job. A、w
On the way home from school, Jack always passes a park. His mother said it was dangerous to pass by the park at night, but it is the fastest way home. Today, after finishing soccer practice, Jack w
是方程
的两个实根，若不等式
对任意实数
恒成立，则实数
的取值范围为 ．
