单选题The split between humans&

问题补充：

单选题Thesplitbetweenhumansandlivingapesisthoughtbysomescholars____15to20millionyearsago.A.to occurB.occurringC.to have occurredD.having occurred

答案：

C解析本题考查非谓语动词。 be thought to do“被认为做某事”，因为后边是 15 to 20 million years ago 已经发生了，因此用不定式的完成式。