Scientists have studied the migration of fish over long distances.
科学家研究过鱼类远距离回游的现象。
A movement from one place to another, as by going by, through, over, or across; transit or migration.
通过从一处到另一处的移动，如经过、穿过、越过或横穿；转移或迁移
There was a huge migration of people into Europe because of the war.
因为战争，大量的移民涌入欧洲。
