问题补充:
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
答案:
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。