典型霍乱病人的重要症状是（）
A.里急后重，脓血便
B.颜面潮红，步行蹒跚
C.剧烈头痛
D.以剧烈腹泻开始
E.黄水样或清水样便
参考答案：D, E
淀粉是无蛋白食品。( )
At school, some students are active ______ some are shy, yet they can be good friends with one another.
A．while
B．although
C．so
D．as
