自然灾害和意外事故的客观存在是保险产生的()。
A.客观基础
B.经济基础
C.自然基础
D.社会基础
参考答案：C
轻微病变性肾小球肾炎临床不出现（）。
A.高度水肿
B.血尿
C.低蛋白血症
D.高脂血症
E.大量蛋白尿
His grandfather _____ since two years ago. [ ]
A. died
B. has died
C. has dead
D. has been dead
