Is "at a time" correct?

Question

I would like to find a way to express the meaning of "at some time". For example: > I think everyone has his study or working rhythm **at a time**. This rhythm varies for different person, and may be different **at a different time** for the same person. Especially it can > change over time as he becomes more experienced. So pacing them at a pre-fixed pace may not work well. **At a time** sounds awkward to me. What do you think?

Answer 1

Usually when using the expression "at a time" it is preceded by a quantity e.g. "one at a time", "two at a time". This indicates that a quantity of people or things did something together at a time during an event that was already made known to the reader or listener.

To use time in the manner you intend you have to add an adjective and pluralize time to times. For example "at certain times", "at different times", "at specific times".

In your example you can lose the first instance of the expression and just say "I think everyone has his own study or working rhythm." Your next sentence where you say the rhythm "varies" indicates to the reader that you will start showing the changes of rhythm for different people as well as the same person.

In the second sentence you also need to change time to "times". So the sentence would read "and may be different at different times." The quantity of time should agree with being plural as you've indicated the variety possible already.

One other thing is that you should use people instead of person when you say that the "rhythm varies for different person," so it should read "rhythm varies for different people". Some people will say you can use "persons" here and though they are correct, they are wrong.