出口食品卫生注册证书的有效期为3年。()
参考答案:对
Last year, Li Hua, a college student, _____ to work for the Olympic Games. [ ]
A. is chossing
B. is chosen
C. was choosing
D. was chosen
金黄色葡萄球菌感染青霉素高度过敏时使用()
A.红霉素
B.氯霉素
C.阿奇霉素
D.甲硝唑
E.利福平