风湿性心内膜炎的特征性病变是（） ["心瓣膜水肿","心瓣膜溃疡、穿孔","心瓣膜混合血栓形成","心瓣膜闭锁缘上疣状血栓形成","心瓣膜增厚变形"]
下列关于风湿病的病因和发病机制的叙述哪项是错误的() ["A．本病多始发于儿童","B．患者血清抗链球菌抗体滴度明显升高","C．多见于热带地区","D．发病前多先有急性扁桃体炎和咽峡炎","E．抗生素的广泛应用，降低了风湿病的发病率"]
风湿性心包炎时心包脏层病变属于() ["A．肉芽肿性炎","B．纤维素性炎","C．化脓性炎","D．浆液、纤维素性炎","E．特异性增生性炎"]
蛛网膜下隙出血最常见的病因是() ["A．高血压","B．脑动脉粥样硬化","C．先天性脑底动脉瘤","D．脑血管畸形","E．血液病"]
关于梭形动脉瘤，下列说法正确的是（） ["A．多为先天性","B．很少破裂","C．多位于颈内动脉系统","D．多有症状","E．颅内最常见"]
如图所示a为脊髓的哪根血管，试述其供血范围及缺血的临床症状?
