多选题
Farming had been profitable on the Great Plains for many decades, but by 1938 ______ agricultural practices and years of inadequate precipitation had ______ the land.
【正确答案】
C、E
【答案解析】[解析] ●but说明前后反义重复；and说明前后同义重复。
●第二空与profitable(赚钱的)反义重复。sustain维持，denude使……光秃，fertilize使肥沃。答案选E。
●______ agricultural practices与years of inadequate precipitation同义重复，都是对土壤不好的东西。shrewd机敏的，conscientious仔细的，imprudent不明智的。答案选C。