瓦斯爆炸条件中瓦斯浓度的界限为（）。
A.9～16%
B.5～16%
C.9～12%
D.5～12%
参考答案：B
下列大叶性肺炎早期影像，哪项不对（）
A.局限性肺纹理稍多
B.支气管气相
C.患肺透亮度略减低
D.发生于下叶者，邻近膈肌动度减低
E.大叶性肺炎早期，影像表现缺乏特征性
Alice was supposed _____ at home, but her mother found her surfing the Internet．
A．studying
B．to be studying
C．to have studied
D．studied
