Research has been limited to production profits, rather than that GM foods are safe.
A. increasing; make sure
B. increasing; making sure
C. increase; make sure
D. increase; making sure
网友回答
A. increasing; make sure
(答案→)B. increasing; making sure
C. increase; make sure
D. increase; making sure
解析： be limited to局限于，to 为介词，故接动名词，rather than 后接动词原形，故选A。句意：研究者只局限于生产利润而不是确保转基因食品的安全性。