化简a-b-(a+b)的结果是[ ]
A.0
B.2b
C.-2b
D.b
答案:C
下列物质互为同分异构体的一组是
A.35Cl和37Cl
B.CH3CH2OH和CH3OCH3
C.O2和O3
D.H2O和H2O2
The wedding of Prince William was held in Westminster Cathedral ______ April 29, 2011.[ ]
A.at
B.in
C.on
D.by