军团菌肺炎抗菌治疗首选（）。
A.红霉素
B.氯霉素
C.青霉素
D.先锋霉素
E.氧氟沙星
参考答案：A
—Don't forget to post the letter, will you?
— I __________ it. [ ]
A. would post
B. had already posted
C. have already posted
D. was posting
胆囊结石形成的主要因素是（）
A.胆固醇增加
B.胆汁淤滞
C.胆盐增加
D.胆固醇减少
E.卵磷脂增加
