It is reported that the underground system      in Changsha now will be open in 2015.

A．is being built

B．built

C．being built

D．is built

气胸的典型X线表现哪项不正确（）。

A.患侧胸腔透亮度增加

B.肺压缩征

C.可见气胸带

D.少量气胸不易发现时嘱患者深吸气，从而易于显示气胸带

E.血气胸时可见液气平面