撒哈拉沙漠以南的非洲大陆只有百分之四的农田得到灌溉。这就意味着大部分农民，尤其是小块土地的经营者，都是靠天吃饭。
Only 4% of farmland in sub-Saharan Africa is irrigated, which means that most farmers, especially smallholders, rely on rainfall to feed their crops.
这些防护林带有效地保护了农田，使之免受流沙侵袭。
These tree belts effectively protect the farmland against shifting sand.
今天，美国百分之八十种植黄豆、玉米和棉花的农田都经过了基因改造。
Today eighty percent of the cropland for soybeans, maize and cotton in the United States is transgenic. Genetic engineering adds or changes genes in a plant to produce desired qualities.
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