People living in the desert choose to keep their ancient lifestyles and customs, _______people in cities throw away their cultural traditions.

A．when

B．if

C．unless

D．while

引起右上腹部阵发性绞痛的疾病有（）。

A.肝癌

B.肝脓肿

C.胆石症

D.急性胰腺炎

E.十二指肠球部溃疡