A:①②③
B:①②④
C:①③④
D:②③④
6 C
12.01
7 N
氮
14.00
8 O
氧
16.01
The company never ____(妥协) on the quality of its products.
我国海拔最高同时被誉为“聚宝盆”的盆地是( )