2．命题＂$\exists \mathrm{x}_{0} \in \mathrm{C}_{\mathrm{R}} \mathrm{Q}, \quad x_{0}^{3} \in \mathrm{Q}$＂的否定是
A $\quad \exists \mathrm{x}_{0} \notin \mathrm{C}_{\mathrm{R}} \mathrm{Q}, \quad x_{0}^{3} \in \mathrm{Q}$
B $\exists \mathrm{x}_{0} \in \mathrm{C}_{\mathrm{R}} \mathrm{Q}, x_{0}^{3} \notin \mathrm{Q}$
C $\forall \mathrm{x}_{0} \notin \mathrm{C}_{\mathrm{R}} \mathrm{Q}, \quad x_{0}^{3} \in \mathrm{Q}$
D $\forall \mathrm{x}_{0} \in \mathrm{C}_{\mathrm{R}} \mathrm{Q}, x_{0}^{3} \notin \mathrm{Q}$
参考答案D