Mark was a student at this university from 1999 to 2003, ____ ,  he studied very hard and was made Chairman of the Students' Union.

A．during which time

B．for which time

C．during whose time

D．by that time

主水饮，肾虚水泛，气血受困的面色特点是（）

A.面色白

B.面色黧黑

C.眼眶黑

D.面色紫黑

E.黄如烟熏