立位片上，腹部游离气体的典型影像为（）
A.球形
B.不规则形
C.新月形
D.半球形，有"气液面"
E.与胸腔间距大于15mm
参考答案：C
You _____come to his office. Our boss won't be back until next week. [ ]
A. haven't to
B. won't have got to
C. haven't got to
D. don't have got to
根端分（）四个区域。
A、根冠
B、生长点（生长锥或者分生区）
C、伸长区
D、根毛区
E、根径
