over 从一边翻越至另一边,如climb over the wall,mountain
across 从同一平面的这边到那,如walk across the street,
through 穿透立体 go through the forest
past 空间为路过,时间为经过
along 沿着“一座横跨江面的桥”怎么说？（两种）a bridge over the river 指与河面垂直 a bridge across the river 指跨越江河