单选题 They are said ______ folk songs now in an Indian tribe.
A. collecting B. to collect
C. to be collecting D. to have collected

【正确答案】 C

【答案解析】[解析] be said to be doing“据说正在……”be said to后面跟的不定式进行式表示在句子谓语动作(be said)发生时主语正在进行中的动作。be said实际上是“有人说”(people say)的被动态。