正常人平卧时，颈外静脉在锁骨上缘至下颌角间的充盈水平在（）
A.不显露
B.下2/3以内
C.下1/2以内
D.下1/3以内
E.以上都不对
参考答案：B
初产妇第一产程约需（）
A.11～12小时
B.6～8小时
C.1小时
D.1～2小时
E.5～15分
_______ , I lost heart in English learning, but my teacher often said to me, “Keep on working hard and you’ll succeed_______”.
A．At a time, in time
B．At a time, on time
C．At one time, in time
D．At one time, on time
