英语 高二 填空题 较难

描述观察与发现的常用表达 — 英语填空题

外研社版·英语(高中) Unit 5 Revealing nature AI 三重审校通过

题目
完成句子:After years of fieldwork in the rainforest, the biologist finally ___ ___ (得出结论,短语) that the rare orchid only blooms after heavy rainfall, which was based on her careful ___ (观察) of over a thousand plants.