题目

如图，在Rt△ABC中，∠ABC=90°，AB=8cm，BC=6cm，点D以每秒1cm的速度从点C出发，沿边CA往A运动，当运动到点A时停止。若设点D运动的时间为t秒，则 当t=时，△CBD是等腰三角形。 答案：【1】5或6或7.29. John was late school because his alarm clock didn't .   A. for;go down   B. for;go off   C. in;get up   D. for;get down