打预防针能预防某些传染病，与这种免疫作用关系最密切的细胞器是[ ]
A．核糖体
B．内质网
C．染色体
D．线粒体
答案：A
.国际上习惯将俄罗斯划分为哪一大洲国家（ ）
A．亚洲
B．北美洲
C．欧洲
D．非洲
Mr. Wang is ______ his wife in social standing(地位), because his wife has made more contributions to our society than he has.
A．above
B．below
C．over
D．under
