The fields where crops used to be grown for building now.
A. have used
B. have been used
C. are being used
D. are used
网友回答
A. have used
B. have been used
(答案→)C. are being used
D. are used
解析：考查时态。本题的关键词是句末的now，说明本句讲述的是现在的情况，句意：过去用来长粮食的地方现在被来来建设大楼了。根据句意说明的是正在进行，正在发生的事情，故使用现在进行时的被动语态。故C正确。