氟里昂制冷剂气体在空气中的浓度百分比达到（）以上时，会使人呼吸困难，甚至窒息死亡。
参考答案：0.3
It is reported that up to now, mountain slides have cut off more than ten villages from the outside world,
_____ more than 100 hundred people alive and _____ many houses. [ ]
A. buried; destroyed
B. burying; destroying
C. to bury; to destroy
D. being buried; being destroyed
在武术教学中，示范的面有几种如何采用？
