从事特种作业的劳动者必须经过专门培训并取得（）证书。
参考答案：特种作业资格
As the busiest woman in the village, she made _____ her duty to look after all the other people’s affairs in that village.
A．this
B．that
C．one
D．it
作为X线照片影像的可供诊断的密度范围是（）
A.0.5～1.0
B.0.5～2.0
C.0.25～2.0
D.0.25～2.5
E.0.5～2.5
