一匹7岁种公马,低热,口干,性欲下降,粪干尿少,舌红苔少,脉细数治疗该病证常选用哪一类药物().
A.补气药
B.补血药
C.滋阴药
D.助阳药
E.清热药
参考答案:C
Sarah had her washing machine repaired the day before yesterday, ____ she?
[ ]
A. had
B. did
C. hadn't
D. didn't
试述零知识证明的原理。