How ______ universe came into being is a puzzle to ______ scientists of all generations.

A. the; 不填    B. an; the    C. a; 不填    C. 不填；the

How ______ universe came into being is a puzzle to ______ scientists of all generations.

   A. the; 不填    B. an; the    C. a; 不填    C. 不填；the

How ______ universe came into being is a puzzle to ______ scientists of all generations.
A. the; 不填    B. an; the    C. a; 不填    C. 不填；the

 How ______ universe came into being is a puzzle to ______ scientists of all generations.

   A. the; 不填    B. an; the    C. a; 不填    C. 不填；the