The purpose of her talking to me last night actually _______this: That I shall never trust him any more in future.

A．comes round

B．comes out

C．comes on

D．comes to

了解某学校在校生视力减退情况，从全校30个班中，随机抽取6个班，并对这6个班中的所有学生做调查。这种抽样方法称为

A．单纯随机抽样
B．机械抽样
C．分层抽样
D．整群抽样
E．分层整群抽样