Swallows begin their migration south in autumn.燕子在秋季开始向南方迁移.Change of climate must have had a powerful influence on migration.气候的变化对于迁移必曾有过极大的影响.Certain other factors are also involved at the secondary - migration stage....
The pulmonary migration of larvae is associated with fever, cough, occasionally hemoptysis.蛔蚴肺部移行,可伴有发热 、 咳嗽 、 偶尔咯血.the seasonal migration of birds鸟的季节性迁徙On migrated sections migration noise can become the equivalent lim...