主要還是糧食生產趕不上高出生率和低死亡率。等到後來化肥，農藥和農業機械以及優良種子後就沒問題了。

來源: 所想即所得於 2016-09-18 08:51:42 [舊帖] [給我悄悄話] 本文已被閱讀：次

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