【题目】To make a breakthrough in his scientific research, the scientist has been making a(n) _____amount of effort.
A. modest B. miserable
C. optional D. tremendous
在线课程【答案】D
【解析】
考查形容词辨析。句意：这位科学家为了让科研有突破，付出了巨大的努力。A. modest谦虚的；B. miserable悲惨的；C. optional可选择的；D. tremendous巨大的，故选D。