下列物质中,属于纯净物的是( )
A.空气
B.食醋
C.生铁
D.氮气
答案:D
Our teacher says that _______ is not right for us to break the rules of the school.[ ]
A. /
B. this
C. it
D. that
男,47岁,3天前因车祸受伤,3小时前出现右侧肢体活动不利。受伤当日在县医院行CT检查未见异常。此时,最大的可能是
A.出现亚急性硬膜下血肿B.迟发性外伤性脑挫裂伤C.因CT质量问题而误诊D.迟发性外伤性脑内血肿E.出现亚急性硬膜外血肿