Many Chinese brands, __________their reputations over centuries,are facing new challenges from the modern market.
A:having developed
B:being developed
C:developed
D:developing
梅雨季节主要发生的地区是( )
水的电离平衡曲线如图所示,下列说法不正确的是( )
距今4500—4000年间,黄河流域各地进入了一个新阶段,一般称为( )