Fixed Expressions and Mixed Practice

Fixed Time Expressions and Mixed Practice

Beyond the systematic rules, English contains a set of time expressions that must be learned as fixed phrases because their prepositions do not follow the general at/on/in scale. The most tested pairs are on time / in time and at the end / in the end. According to exam statistics from Cambridge Assessment, fixed time expression errors appear in approximately 22% of B2 writing exam scripts, most commonly the in/at the end confusion.

On Time vs In Time

On time means punctual — arriving or happening exactly at the scheduled moment. In time means not too late — arriving before a deadline or before something happens:

The train arrived exactly on time. (= at the scheduled time, punctual)
We arrived just in time to catch the train. (= not too late, before it left)
The meeting started on time. (= at the planned time)
She got there in time for the opening speech. (= before it began)

At the End vs In the End

At the end refers to the final point of a specific, identifiable period or sequence — it must be followed by 'of + noun'. In the end means eventually or after a long process of deliberation — it does not require a following noun:

At the end of the film, the hero dies. (final point of the film)
At the end of the day, I was exhausted. (final point of the day)
In the end, we decided to cancel the trip. (eventually, after deliberation)
I didn't enjoy the course at first, but in the end I learned a lot. (eventually)

Other Key Fixed Expressions

I'm quite busy at the moment. (= right now — always 'at', never 'in')
At first, I was nervous. (= in the beginning, when I started)
I'll be back in ten minutes. (interval from now)
We arrived just at the end of the film. (the specific final point)

Common Mistakes

✗ I'm very busy in the moment. → ✓ I'm very busy at the moment.
✗ I didn't enjoy it, but at the end I learned a lot. → ✓ ...but in the end I learned a lot.
✗ I've been working here for 2024. → ✓ I've been working here since 2024.
✗ I was born in 15th March, 1990. → ✓ I was born on 15th March, 1990.
✗ I started school on September that year. → ✓ I started school in September that year.