If you want to study the nature of the universe first of all you must be clear about its

问题补充：

If you want to study the nature of the universe, first of all, you must be clear about its .

A. traditions

B. consequences

C. signs

D. origins

答案：

A. traditions

B. consequences

C. signs

(答案→)D. origins

解析：考查名词辨析。A传统；B结果；C迹象；D起源；句意：如果你想了解宇宙的特征。首先你必须对宇宙的起源很清楚。根据句意说明D正确。