She an English teacher. [ ]
A. uses to
B. used to
C. use to be
D. used to be
答案:D
下述哪些有助于预防坐位麻醉时低血压()
A.腹部加压
B.下肢裹弹性绷带
C.呼气末正压通气
D.扩容
E.保持自主呼吸