下面的内容是2018全国卷2的语法填空题：

阅读下面短文，在空白处填入1个适当的单词或括号内单词的正确形式。

Diets have changed in China—and so too has its top crop. Since 2011, the country ___61___ (grow) more than rice. Corn production has jumped nearly 125 percent over ___62___ past 25 years, while rice has increased only 7 percent.

A taste for meat is ___63___ (actual) behind the change：An important part of its corn is used to feed chickens, pigs, and cattle. Another reason for corn’s rise: The government encourages farmers to grow corn instead of rice ___64___ (improve) water quality. Corn uses less water ___65___ rice and creates less fertilizer (化肥) runoff. This switch has decreased ___66___ (pollute) in the country’s major lakes and reservoirs and made drinking water safer for people.

According to the World Bank, China accounts for about 30 percent of total ___67___ (globe) fertilizer consumption. The Chinese Ministry of Agriculture finds that between 2005—when the government ___68___ (start) a soil-testing program ___69___ gives specific fertilizer recommendations to farmers—and 2011, fertilizer use dropped by 7.7 million tons. That prevented the emission (排放) of 51.8 million tons of carbon dioxide. China’s approach to protecting its environment while ___70___ (feed) its citizens “offers useful lessons for agriculture and food policymakers worldwide,” says the bank’s Juergen Voegele.

【参考答案】61. has grown  62. the  63. actually  64. to improve  65. than  66. pollution  67. global  68. started  69. that / which  70. feeding

 我不太明白下面一句如何分析，尤其是其中的 while feeding 如何分析？

China’s approach to protecting its environment while feeding its citizens “offers useful lessons for agriculture and food policymakers worldwide,” says the bank’s Juergen Voegele.