Entering the reading room,we found her      at a desk,with her attention      on a book. [ ]

A. sitting；fixing    

B. to sit; fixed

C. seating；fixed

D. seated；fixed

过氧化物、高氯酸盐、叠氮铅、乙炔铜、三硝基甲苯等属于易爆物质，受震或受热可发生热爆炸。