第33题: [单项选择]What is the main idea of the text A. organically grown foods are nutritious. B. how to buy organically grown foods. C. what does organically grown foods mean D. a general standard should be established to regulate the organically grown produce. 参考答案:D 答案解析:通读全文可以发现,本文主要论述应当建立一个衡量有机农作物的确切标准。