Bob is weaker than Tim this year. Because he exercise a lot last year.
A:didn't
B:isn't
C:wasn't
下图是“某地地形简图”,M点位于36.5 N。冬至日,甲、乙两个中学生分别到达P和M点,测算出两点相对高度是288米,并观测到该日正午M峰顶的影子正好移至P点。甲学生观测乙学生时(忽略身高),其仰角约为( )
分久必合,合久必分,我国历史上由分裂走向大统一的朝代不包括( )
圆x2+y2-4x=0的圆心坐标和半径分别为( )