黄土高原与南方地区的重要界线是:( )
A:淮河
B:秦岭
C:太行山
D:大兴安岭
指南针之所以能指南北是因为受到____ 的作用.科考人员把一条形磁铁带到地球某极地后,用细绳悬挂,其在水平位置平衡的情景如图所示,由此可知所在位置为地理____ (选填“南”或“北”)极.
—Which is _______, the Yangtze River or the Yellow River?
—The Yangtze River, of course.
You are supposed to ____ smoking, ___________ you will get ill.