贫血最常见临床表现是（）。
A．窦性心动过速
B．心脏杂音
C．皮肤和黏膜苍白
D．口腔炎、舌炎
E．毛发干燥无光泽、易脱落
参考答案：C
Oligopolists have an incentive to cheat on collusive agreements in order to:（）
A. avoid competitive practices.
B. restrain trade and hinder trade relationships.
C. increase their individual share of the joint profit.
消毒用新洁尔溶液的浓度是（）。
A.0.1%
B.5%
C.10%
D.20%
