治疗并殖吸虫病的首选药物是（） ["喹诺酮","别丁","三氯苯达唑","氯喹","吡喹酮"]
与急性脊髓炎腰穿不符的一项是（） ["糖、氯化物正常","压颈试验通畅","外观五色透明","蛋白明显减低","CSF压力正常"]
患门静脉高压症时患者可有（） ["门静脉扩张","在门静脉与体循环中有侧支循环吻合","脾肿大","腹水","以上各项均是"]
伤寒杆菌的主要致病因素（） ["外毒素","伤寒内毒素","细菌的侵袭力","H抗原","肠毒素"]
重症肌无力病人出现胆碱能危象时临床表现为（）。 ["瞳孔缩小，分泌物增多","腹痛，汗多","肌束颤动","高热，血压降低","恶心，呕吐"]
简述定额的基本特征。
