下呼吸道感染的常见因素为( )
A.免疫功能受损
B.正常菌群失调
C.病原体的飞沫传播
D.空调系统污染
E.致病菌通过气道逆行感染
参考答案:A,B,C,D,E
The Smiths decided Paris on vacation. [ ]
A. went to
B. to go to
C. to go
D. go to
作业中对防护员有何作业标准及要求?