【正确答案】 China has found many offshore oilfields since the beginning of the reform and opening up.

【答案解析】 以前，人类只在陆地发掘石油，那时油田叫oilfield。后来，人类又在海上发现了石油，并给海上油田起了个名字叫offshore oilfield。有趣的是，为了避免混淆，陆上油田也改名换姓，仿照海上油田，改叫onshore oilfield了。