an important decision more on emotion than on reason you will regret it sooner or later.A

问题补充：

an important decision more on emotion than on reason, you will regret it sooner or later.

A. Based

B. Basing

C. Base

D. To base

答案：

A. Based

(答案→)B. Basing

C. Base

D. To base

解析：考查非谓语动词。句意：“基于情感大于理智作出的一项重要决定，你将迟早忘记。”现在分词basing动作与后面主句主语you构成逻辑上的主谓关系，表条件，相当于“if you base…”。