While they ____(discuss) how to prevent accident, another accident happened.
根据如图“南极地区略图”,完成问题.
我国四个南极科学考察站中,无极昼极夜现象的是( )
函数y=cos(2x+π4)的图象的一条对称轴方程为( )
Although many Americans move a lot, they still________and understand each other's dialects.