It's ten years since the scientist on his life's work of discovering the valuable chemical.
A. made for
B. set out
C. took off
D. turned up
网友回答
A. made for
(答案→)B. set out
C. took off
D. turned up
解析：此题考短语动词。句子合理的意思应是：自从那位科学家着手／开始去为发现这一有价值的化学物质而工作。至今已经10年。选B项表开始或着手某事，即set out to do sth.或set out on sth.正合理。make for不是固定短语，只能解释为“为……而做”，take off当“脱下（衣物）、从……取下……、（飞机）起飞”等解，turn up意为“出席、露面”，这三项均不合题意。