禽流感主要发生于() ["主要发生于夏季","主要发生于冬季","主要发生于夏秋有蚊子的季节","主要发生于春季","一年四季都发"]
红霉素在下列哪种组织中浓度较低() ["脑","肝","肺","胆汁","脾"]
猪瘟主要发生于() ["主要发生于夏季","主要发生于冬季","主要发生于夏秋有蚊子的季节","主要发生于春季","一年四季都发"]
猪传染性胃肠炎和猪流行性腹泻发生于() ["主要发生于夏季","主要发生于冬季","主要发生于夏秋有蚊子的季节","主要发生于春季","一年四季都发"]
红霉素不是下列哪些疾病的首选药物() ["白喉带菌者","骨髓炎","空肠弯曲杆菌肠炎","婴幼儿支原体肺炎","军团菌病"]
产生矿尘的主要作业工序有哪些?