A:CH3CH2CHBrCH2Br
B:CH3CH(CH2Br)2
C:CH3CHBrCHBrCH3
D:(CH3)2CBrCH2Br
求几个加数的和,用乘法计算比较简便.
史书上记载春秋时期“公作则迟”“分地则速”。出现这种现象的主要原因是( )
一Cheer up! You will make it if you try your best.
一Thank you.I will.