The ice crystals must be oriented horizontally and the observer's line of sight must be close to horizontal to see the sundogs.
冰晶必须面向水平，而观察者的视线也必须接近水平来观察幻日。
2
Indeed, horizontal lines are similar to the familiar sight of a horizon line in the distance allowing them to convey a sense of wide-open space.
事实上，横线与熟悉的景物——远方的地平线相似，由此，它们适于传递一种辽阔空旷之感。
3
The reasons of five error sources including vertical axis, horizontal axis, sight line coder, TV undershooting value which can result in TV tracking system errors are analyzed.