问题详情：
---That woman has been taking care of the two white tigers for 8 years.
---Oh, dear! She ______ a lot of difficulties!
A. could go through B. might go through
C. ought to have gone through D. must have gone through
【回答】
D must+完成时表示对过去事实的肯定推测。
知识点：虚拟语气与情态动词
题型：选择题