常引起主胰管多发性结石的胰腺病变是（）
A.胰腺假性囊肿
B.慢性胰腺炎
C.功能性胰岛细胞瘤
D.胰头癌
E.急性胰腺炎
参考答案：B
We were all doing our history paper in the classroom yesterday evening________the light went out.[ ]
A. since
B. before
C. while
D. when
“君子周而不比”是指君子不喜欢与人比较。
