Seven days _____ a long time, I think. [ ]
A. are
B. is
C. an
D. have been
答案:B
为什么说财政活动的主体是政府?
脑血栓形成的最常见病因是()
A.血液高凝状态
B.动脉粥样硬化伴高血压
C.先天性血管畸形
D.真性红细胞增多症