Generally, the reason for such seasonal back-and-forth movement is to seek resources that aren't available within a single area year-round.
一般来说,进行这种季节性往返迁移是为了寻找在一个地区无法全年获得的资源。
2
Seasonal factors, such as the rainy season, along with population movements in the area contribute to this unusually high incidence of cholera.
雨季等季节性因素以及该地区的人口流动造成这一极不寻常的霍乱高发病率。
3
Seasonal factors, with a particularly heavy rainy season, along with increased population movements in the area contribute to this unusually high incidence of cholera.