As noted in How to make the most of coaching, it’s always useful when students asking for help tell me their deadlines. But sometimes they get more than they bargained for:

If you have time today until about 9 p.m. could you please correct it?

Will it be possible to receive it back from you until Thursday, Dec. 13?

Instead of until, both students meant before or by. (Yes, I edit e-mail.) What’s the difference?

Until means the entire time up to a particular point. So if you ask if I can look at your work until Dec. 13 — well, it’s April, and you’re asking for an awful lot of time. If, on the other hand, you ask me to do it before or by (up to and including) that time, you’re asking if I can do it at any point in advance of your deadline. So:

If you have time today until before about 9 p.m. could you please correct it?

Will it be possible to receive it back from you until by Thursday, Dec. 13?

Today, a Tow-Knight fellow wrote: I have to complete an article within tomorrow. She meant by; within means inside. You can do something within a span of time, as in I have to finish it within a day, but not “within tomorrow.” Or she could have just said: I have to complete an article  tomorrow.

Another told me, “I have to apply on May 20.” She, too, meant by. On May 20 means she can apply on that day only, not that it’s the deadline.

Jo Bruni got it right when she wrote:

Gregory Spock, 34, a real estate broker in Queens, said millennials have paid off a good part of their student debt by the time they come to him looking for a home in New York.

Other time words — specifically as and since — cause confusion because they don’t always refer to time. Last fall I found myself explaining the same point to the third student in one day (and the fourth in two):

The school has had to move several times as it does not have a permanent space of its own.

Thankfully, she is slowly understanding them now as her grandparents tend to use simple words while communicating with her.