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：考查动词词组辨析。Make for 导致，有助于 set out 出发，开始做某事 take off 起飞，事业腾飞 turn up 出现
句意为自从科学家开始他的发现有价值的化学物质的工作，已经有10年了。