题目

He was so ________ thought that he didn't see the pole on the road. A . buried in B . careful with C . busy with D . serious about 答案：A2．一艘轮船在江中向正东方向航行，在点P处观测到灯塔A、B在一直线上，并且此直线与航行方向成30°角，轮船沿航线前进600米到达C处，此时观测到灯塔A在北偏西45°方向，灯塔B在北偏东15°方向．求两灯塔之间的距离．