Frank is very lonely, he has few friends, _____? [ ]
A. does he
B. doesn't he
C. is he
答案:A
木通主含()。
A.生物碱
B.蒽醌
C.皂苷
D.黄酮
E.木脂素
呼吸机相关性肺炎最重要的预防措施是()
A.声门下分泌物引流
B.呼吸机的湿化器用无菌水
C.定期更换管道
D.做好气道护理
E.采取综合措施