On second thought I decided to give him second choice.A. a ; aB. a ; theC. the ; aD. the

问题补充：

On second thought, I decided to give him second choice.

A. a ; a

B. a ; the

C. the ; a

D. the ; the

答案：

A. a ; a

B. a ; the

(答案→)C. the ; a

D. the ; the

解析：句意：在第二次沉思了一下后，我决定给他再一次机会。the second表示第二次，a +序数词，表“再一次，又一次”，故选C