问题
选择题
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
答案
答案：B
题目分析： 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。
点评：要熟记语法规则：介词to后接名词，代词，或动名词，rather than 后接动词原形，另外prefer to do sth rather than do sth也是常考结构
