六氟化硫(SF6)是一种()的惰性气体,化学性能稳定,有优良的灭弧和绝缘性能。()
A、无色
B、无嗅
C、比重比空气小
D、无毒
E、不可燃
参考答案:A, B, D, E
Audiences were greatly ______ by the video class about weightless conditions _____ in Tianggon-1 space station.
A.impressing; presenting
B.impressed; presenting
C.impressing; presented
D.impressed; presented
高速公路经营单位不依法履行高速公路养护、绿化和高速公路用地范围内水土保持义务的,()应当责令其限期履行。