1.B由意得,U={01,2,3,4,5,6,78,9,则={0.2,4,5,7.89}∴(c)n={0,2,589,故选B2.D由题意得,“若a>B,则sina>sinB的逆否命题为“若sina≤sin,则a≤故选D3.A∵2=x+yi-i=2x+(y-1)=2,∴动点(x,y)的轨迹方程是x2+(y-1)2=4.故选A4.B作出不等式组所表示的平面区域如图阴影部分所示,目标函数z=x+y,观察可知,当直线y=-x+z过点A(79)时,z有最大值16,故选B