— I'm afraid you _________. It's a non-smoking area.
A:couldn't
B:needn't
C:don't
D:can't
公差不为零的等差数列an的前n项和为Sn.若a4是a3与a7的等比中项, S8=32,则S10=( ).
已知p:a﹣4<x<a+4;q:(x﹣2)(x﹣3)>0,若q是p的必要条件,则a的取值范围是____ .
David can cook the meals ,__________Nancy can't .