治疗肝经风热，目赤肿痛，宜选用（）
A、柴胡
B、牛蒡子
C、葛根
D、蝉蜕
E、升麻
参考答案：D
已知集合A={x|ax2-ax+1＜0}，若A=ф，则实数a的集合为（ ）
A．{a|0＜a＜4}
B．{a|0≤a＜4}
C．{a|0＜a≤4}
D．{a|0≤a≤4}
No one knows exactly when our ancestors started talking，but new evidence suggests _______might have happened a long time ago．
A．which
B．what
C．it
D．they
