氢化物发生原子化法主要用于测定As、Bi、Ge、Sn、Sb、Se、Te等元素,常用的还原剂是( )。
A.NaBH4
B.Na,SO3
C.SnCl2
D.Zn
参考答案:A
Mary worked day and night. She _____ her objective to be admitted by the famous university at last. [ ]
A. refreshed
B. accomplished
C. evolved
D. raised
中央式通风方式是进风井和回风井均位于井田倾向的中央。