migrations

例句:

• It foundered during the turmoils accompanying the Great Migrations.
  它在随着民族大迁徙而出现的混乱中崩溃.
  
• Birds also have built - in timepieces which send them off on fall and spring migrations.
  鸟类也有天生的时间感应器指导它们秋春迁移.
  
• It will bring huge economic and social costs, and cause vast unrest, migrations and potential conflict.
  它将造成巨大的经济和社会耗费, 同时也会引发大面积的动乱 、 移民以及潜在冲突.
  
• Every winter Mexico hosts a pair of extraordinary migrations.
  来自SA
• Internal migrations tend to be from the 'land' towards the regional cities.
  来自BBC
• But further genetic analysis and study should help to clarify these early migrations.
  来自SA