His failure made his father think him a ___________ boy.
A:disappoint
B:disappointed
C:disappointing
D:disappointment
若集合M=x|y=x-1,集合N=y|y=x-2,那么M∩N=( )
关于摩擦力,以下说法正确的是( )
____是黄河干流上最大的水利枢纽。
新航路的开辟使世界市场开始形成,最能够说明这一结论的是( )
雅尔塔体系的实质是( )