已知(a2+b2+1)2=4,求a2+b2的值。
解:a2+b2+1=±2
∴a2+b2=1, a2+b2=-3
∵a2≥0,b2≥0
∴a2+b2≥0
∴a2+b2=1
— Have you heard what Mary asked me?
— Yes. She asked _____. [ ]
A. whether I have got the ticket for the 2012 Olympic Games
B. whether you had got the ticket for the 2012 Olympic Games
C. that I have got the ticket for the 2012 Olympic Games
D. had you got the ticket for the 2012 Olympic Games
国家电网公司的核心业务是()
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B、优质服务
C、建设电网
D、品牌建设