同学你好，该知识点来自沪江网校《英语零基础直达大学六级【7月班】》的课程，想要更系统的学习，欢迎进入课程学习。不仅可以和更多的同学一起学习，而且还有老师、助教随时的学习指导和知识点解答哦。

同学你好~
what the writer saw and did 作者看到了什么，做了什么

when he tried to prevent the ants from climbing up his peach tree 是时间状语从句
preven sth from doing 阻止某物做某事
We must prevent the trouble from spreading.
我们必须防止这个乱子扩大。

what the writer saw and did when he tried to prevent the ants from climbing up his peach tree
当作者试图阻止蚂蚁爬上他的桃树时，他看到了什么，他做了什么

祝同学学习进步~