农业银行三个客服中心分别在（）。
A．天津
B．上海
C．北京
D．成都
参考答案：A, B, D
（a-b）2+2（b-a）2=______．
—Where is your father? —He _____ to Australia on business.[ ]
A. has been
B. has gone
C. went
D. will go
