已知A(a﹣1,3),B(﹣2010,b+2)两点关于原点对称,则a= _________ ,b= _________ .
2011;﹣5.
Girls usually _______ themselves up in popular clothes. [ ]
A. are in
B. wear
C. dress
D. put on
试论述“幅-频”特性曲线所表达的物理意义。