Why go to the expense of buying an electric saw when you can borrow one?

你能借到电锯，却为何去花钱买呢？

《柯林斯英汉双解大词典》

Why go back to the gray, dirty, noisy, rushed life?

为什么要回到那灰暗、肮脏、吵闹和匆忙的生活中去呢？

youdao

So why go to all this effort?

那么这一切努力又是为了什么？

youdao

I did not understand. "But,Dupin," I said, "why did you go to the trouble of replacing the letter?

VOA: special.2009.12.26

Why does he go against the traditional Ancient Near Eastern practice of primogeniture, inheritance by the first born?

为什么他要违背传统古代近东的惯例,也就是长子继承制，由第一个儿子继承？

耶鲁公开课 - 旧约导论课程节选

But you have to submit your test scores, you have to write some essays, like why you want to go to Brown.

但是你必须提交你的成绩单，还要写一些文章，例如你为什么选择布朗大学。

被学问的自由所迷住 - SpeakingMax英语口语达人

Why go back to that old conventional way of just going after discretionary domestic spending?

WHITEHOUSE: Press Briefing

Of course, if classroom content is available digitally, why go to class at all?

FORBES: Digital Teaching Promises to Improve Grades

Why go through the hassle of developing and producing original programming which can be an expensive headache?

FORBES: DirecTV Hoping For 'A House Of Cards'-Like Hit With Original Series 'Rogue'