________, he talks a lot about his favorite singers after class.
A:Quiet student as he may be
B:A quiet student as he may be
C:Be a quiet student as he may
D:Quiet as he may be a student
物质
乙醇
氧气
水
二氧化碳
X
反应前质量/g
4.6
8.0
0
反应后质量/g
5.4
4.4
a
下列判断正确的是( )