---ThewomanbiologiststayedinAfricastudyingwildanimalsfor13yearsbefores

---The woman biologist stayed in Africa studying wild animals for 13 years before she returned．---Oh, dear! She ______ a lot of difficulties!A.may go throughB.might go throughC.ought to have gone throughD.must have gone through

D解析前者所说句意为“这位女生物学家回来之前，在非洲住了13年研究野生动物”。因此后者所说“她一定渡过了很多难关”。这一过程应该是过去的事情，用情态动词对过去情况进行推测，应该用“情态动词+have done”这一结构，故排除A和B项；ought to have done相当于should have done，意为“本应该做某事但事实上没有做”，不符合题意，故排除C项；must have done意为“一定已经做了……”，符合题意。

感谢回答，我学习了