下列运算正确的是[ ]
A．a2a3=a6
B．（﹣a）4=a4
C．a2+a3=a5
D．（a2）3=a5
答案：B
The old woman often feels because she has no children .
A. alone; live with B. lonely; to live with C. lonely; to live
莱布尼茨提出了（）.
A.预定和谐说
B.单子论
C.理性真理
D.心的主动论
