空气的下列成分中，不能充填在食品袋中用于保质的是[ ]
A.二氧化碳
B.稀有气体
C.氧气
D.氮气
答案：C
病人便频，大便变形，首先应查
A．直肠镜
B．乙状结肠镜
C．纤维结肠镜
D．直肠指诊
E．钡灌肠
Jack's ______ of black music and performers into a mainstream art form contributed in crucial but not often noted ways to desegregation.
A．transformation
B．assimilation
C．deviation
D．diversion
