【问】 Jean Wagner’s most enduring contribution to the study of Afro-American poetry is his insistence that it____in a religious，as well as worldly，frame of reference.

A. is to be analyzed B.has been analyzed

C. be analyzed D. should have been analyzed(攻读硕士学位研究生入学考试英语试题，94)

答案为C (be analyzed)。但我弄不懂为什么答案为C。

【答】 见insist，requirement。