It came as shock to learn that Bob one of the top students in our class failed in exam.

问题补充：

It came as shock to learn that Bob, one of the top students in our class, failed in exam.

A. /; the

B. a; the

C. a; an

D. /; an

答案：

A. /; the

(答案→)B. a; the

C. a; an

D. /; an

解析：句意：得知Bob，我们班最好的学生之一，在这次考试中没有及格，很是震惊。第一个空，是泛指，故用不定冠词a；第二个空是特指“这次考试”，故用定冠词 the，选B。