洁净度等级6～9级应采用（）气流流型。
A.垂直单向流
B.垂直或水平单向流
C.非单向流
D.任意
参考答案：C
I believe the government regards the H1N1 as an important thing , and I also believe the officials are so ________ that everything will be under control.
A grateful B determined C willing D peaceful
提高胃癌治愈率的关键是（）.
A.早期诊断
B.根治性手术
C.早期应用抗癌药物
D.术后放疗
E.综合治疗
