A:黄河
B:珠江
C:长江
D:雅鲁藏布江
划分南北半球的纬线圈是( )
The teacher asked the students to stop talking and ____ (listen) to her.
六边形一共有对角线( )
已知复数z=3i-1i(其中i为虚数单位),则复数z的共轭复数z-是 ( )