Many parents died in Wenchuan earthquake, so children were ________ by our government.[ ]

A. taken up  

B. given up

C. grown up  

D. brought up

已知初婚年龄服从正态分布。根据9个人的调查结果，样本均值岁，样本标准差（以9-1作为分母计算）s=3岁。问是否可以认为该地区初婚年龄数学期望值已经超过20岁（α=0.05，用临界值规则）？