下列有关化学用语表示正确的是      [ ]

A．氟化铵的电子式：                    

B．丙烯的结构简式：CH₂CHCH₃

C．铝离子的结构示意图：                

D．甲醛分子的比例模型：

For a long time in that vast region, this law was in abeyance.

A. active use


B. doubt
C. discussion


D. disuse