题目

On an autumn afternoon, I went to a farm with my father. I learnt to plant potatoes there.（用非限制性定语从句合并下列句子） 答案：On an autumn afternoon, I went to a farm with my father, where I learnt to plant potatoes.人眼看到斜插入水中的筷子向上折（如图），如图的四幅光路图中，能正确说明产生这一现象的原因的是（ ）A. B. C. D.