题目

Tomorrow is my_______ birthday, I promise to take on more challenges in my_______．  A. thirty; thirties B. thirtieth; thirties C. thirties; thirtieth   D. thirtieth; thirty 答案：B16．有个篮球从3m高的二楼窗台竖直落下，触地反弹竖直上升1.5m后被另一同学接住，问篮球通过的路程是4.5m，位移大小是1.5m，方向竖直向下．