You can borrow my keys—I have a spare set.

你可以借用我的钥匙—我还有一套。

《牛津词典》

As it happens, I have a spare set of keys in my office.

碰巧我在办公室有一套备用钥匙。

《牛津词典》

Can I have a spare key made?

我可以再配一枚备用钥匙吗？

youdao

And that got me to think gosh, these people have so little and I was a student, and I didn't have a lot of money, but I still had something to spare.

看到这张照片，我想,天啊，这些人太贫困了,虽然我是个学生，我没有很多钱，但我还是能够捐出些什么的。

普林斯顿公开课 - 人性课程节选

But as you get older and you have a lot of spare time, you think about what you are doing, which is something I have the luxury of doing right now, and I realized this is more tricky.

但随着你们年龄的增长,有更多空闲时间之后,你就会思考你做的事情,我现在就有很多闲暇思考这些问题,我意识到这东西其实很精妙

耶鲁公开课 - 基础物理课程节选

Since I don't have a lot of cash or time to spare, I have not been able to keep it up very well.

WSJ: Are Sellers' Appraisals and Inspections Overkill?--WSJ House Talk

Having learned what the Gateses have done for the needy in different parts of the world, I am wondering if they can spare a thought for the have-nots in Vietnam.

FORBES: Readers Say: Philanthropy and The Forbes 400

And if you have spare time, I hope we can talk even for a few minutes.

FORBES: Letter From Mom and Dad