某省从3个水中氟含量不同的地区随机抽取10～12岁儿童，进行第一恒齿患龋率的调查，结果如下表：

应计算的统计量为（）

A.X²

B.t

C.F

D.u

E.以上全不对

She _____ his number in the phone book to make sure that she had got it right. [ ]

A. looked up

B. looked for

C. picked out

D. picked up