No matter how bright a talker you are there are times when it is better silent.A. remain

问题补充：

No matter how bright a talker you are, there are times when it is better silent.

A. remain

B. be remaining

C. to remain

D. having remained

答案：

A. remain

B. be remaining

(答案→)C. to remain

D. having remained

解析：考察不定式做主语用法。本句中的不定式to remain silent在句中作真正的主语，前面的it是形式主语。句意：无论你是一个多么聪明的谈话的人，也有一些时候最好要保持沉默。不定式做主语的时候，表示的是一次性具体的行为，故C正确。