英文英文字典

英文英文字典

古腾堡计划中的在线英语-英语词典

结果

Backsight的结果

Backsight (n.)
The reading of the leveling staff in its unchanged position when the leveling instrument has been taken to a new position; a sight directed backwards to a station previously occupied. Cf. Foresight, n., 3.