至于什么原因，我们无从得知，是否因为一场战争，也可能移动到城市了，或者迁移到了巨大的集体农庄，没有人知道确切的答案。

What was the reason for that - nobody knows; whether it was a war, a sprouting possibility to move to the biggest cities or a policy of kolkhoz sprawling, there is no exact answer.

youdao

提出了可逆迁移过程和不可逆聚集过程共存的聚集体生长模型。

A kinetic model of the growth of aggregates driven both by reversible migration and by irreversible aggregation is proposed.

youdao