direction key方向键directionn.方向；指导；用法说明；趋势；目标；管理directional purification定向提纯direction representation直接表示法direction finding picket测向哨directional quantization方向量子化directional well drilling定向井钻井direction of current flow电流方向direction for development发展方向direction finding message测向信息direction finding problem定向寻找问题direction of regeneration更新方向