In winter, they cannot find enough food in the north, so they fly in autumn. ( )
朝诗人王维出使到边塞，被眼前的奇异风光所震撼，写下了“大漠孤烟直，长河落日圆”的名句。无独有偶，宋代范仲淹在边塞军中也对这奇异风光作过描写，其诗句是：____ ，____。
