This paper discusses the types of grain yield reduction, and chooses 1998 and 2003 as representative years to study the grain yield reduction at national, provincial and county scales.
本文选取1998和2003年为典型年份，从国家、省级、县域3种尺度对中国粮食减产进行研究。
In 1959, various factors such as reduction of sown areas, less yield per unit area and natural disasters contributed to the decrease in grain output.
1959年开始，由于播种面积减少、单产下降、自然灾害等原因，粮食产量连年下滑。
In 1959, various factors such as reduction of sown areas, less yield per unit area and natural disasters contributed to the decrease in grain output.
1959年开始，由于播种面积减少、单产下降、自然灾害等原因，粮食产量连年下滑。
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