Expressions with no preposition
At/on/in are not normally used in expressions of time before next, last, this, that (sometimes), one, any (in an informal style), each, every, some, all.
|See you next week.
Are you free this morning?
I’m at home every evening.
We stayed all day.
|Come any time.
I didn’t feel very well that week.
Let’s meet one day.
These prepositions are not normally used, either, before yesterday, the day
before yesterday, tomorrow or the day after tomorrow.
- What are you doing the day after tomorrow?
And prepositions are usually dropped in questions beginning What/Which + expression of time, and in answers which only contain an expression of time.
- What day is the meeting?
- Which week did you say you’re on holiday?
- What time are you leaving-: Eight o’cloc