关于急性胆囊炎正确的是()
A.持续性右上腹痛,阵发性加剧
B.一般有寒战
C.只有少数人出现黄疸
D.大多数是在活动后发病
E.可在进油腻食物后出现
参考答案:A, C, E
With ail the magazines I needed _________,I left the post office.
A.buying
B.to buy
C.bought
D.to be bought
给出集合序列{1},{2,3},{4,5,6},{7,8,9,10},…,设Sn是第n个集合中元素之和,则S21为( )
A.1113
B.4641
C.5082
D.5336