A:巫山以西是四川盆地
B:横断山脉以西是云贵高原
C:昆仑山以南是青藏高原
D:大兴安岭以东是东北平原
如下图所示,A、B、C是圆O上的三点,CO的延长线与线段AB交于圆内一点D,若OC→=xOA→+yOB→,则 ( )
— I can't stand (忍受) the air pollution in this city any more. It is getting more terrible.
— ________. We've never had so many factories before.
如图是一个照相机成像的示意图,如果底片AB宽40mm,焦距是60mm,所拍摄的2m外的景物的宽CD为( )