— _________ do you have an Art Festival in your school?   — Once a year.

A．How long

B．How often

C．How far

D．How soon

食管静脉破裂大出血的内科治疗，宜首选（）

A.止血药

B.输液扩容

C.冰盐水+肾上腺素洗胃

D.三腔管气囊压迫

E.持续胃肠减压