①CH3(CH2)2CH3
②CH3(CH2)3CH3
③(CH3)3CH
④(CH3)2CHCH2CH3.
A:②④①③
B:④②③①
C:④②①③
D:②④③①
一Are these your tomatoes?
一Yes. They are .
解:∵m2﹣2mn+2n2﹣8n+16=0,∴(m2﹣2mn+n2)+(n2﹣8n+16)=0,
∴(m﹣n)2+(n﹣4)2=0,又∵(m﹣n)2≥0,(n﹣4)2≥0,
∴ {(m−n)2=0(n−4)2=0 ,∴n=4,m=4.
请解答下面的问题:
如图,已知AB∥CD,OM是∠BOF的平分线,∠2=70°,则∠1的度数为( )
They are_______.