You must observe and gather information like Nicolaus Copernicus you want more career advancement opportunities.
A. or
B. because
C. unless
D. if
网友回答
A. or
B. because
C. unless
(答案→)D. if
解析：这题考查连词的用法：句意是：你必须观察收集Nicolaus Copernicus的信息，如果你想要更多的事业进步机会。选D。