∴a2x2+b2y2+b2x2+a2y2≥a2x2+b2y2+2abxy,
即(a2<
As you are not feeling well, you'd better_______ to school.
南宋都城临安是今天的哪个城市( )
根据下列实验现象可以判断某溶液一定呈碱性的是( )