Again, I don't have data to back this up, but just common sense suggests to me that the common case is if I'm on the subway platform I want to get on that train and maybe I want to get back and where are those two buttons, right?

此外，我没有数据来备份这个，但是常识告诉我，常见的情况是,如果我站在地铁站台上，我想乘上地铁,可能我还想回来,那么哪里能找到这两个按钮，对不？

哈佛公开课 - 计算机科学课程节选

We're talking about like, if you didn't, even if you had all your data on your computer backed up on hard drive,

如果你没有将你电脑里的数据备份到硬盘里，

没有智能手机活不了 - SpeakingMax英语口语达人