A. 隐性感染 B. 活动性感染 C. 急性感染 D. 先天性感染 E. 慢性感染
A. 乙型脑炎 B. 乙型肝炎 C. 流感 D. 水痘 E. 脊髓灰质炎
A. is B. are C. was D. were