Main points

* Adverbials of time can be time expressions such as `last night’.

* Adverbials of time can be prepositional phrases with `at’, `in’, or `on’.

* `For’ refers to a period of time in the past, present, or future.

* `Since’ refers to a point in past time.

1 You use adverbials of time to say when something happens. You often use noun groups called time expressions as adverbials of time.

yesterdaylast nightnext Saturdaythe day after tomorrow
todaylast yearnext weekthe other day
tomorrow

Note that you do not use the prepositions `at’, `in’, or `on’ with time expressions.
One of my children wrote to me today.
So, you’re coming back next week?

You often use time expressions with verbs in the present tense to talk about the future.
The plane leaves tomorrow morning.
They’re coming next week.

2 You can use prepositional phrases as adverbials of time:

* `at’ is used with:

clock times:at eight o’clock, at three fifteen
religious festivals:at Christmas, at Easter
mealtimes:at breakfast, at lunchtimes
specific periods:at night, at the weekend, at weekends, at half-term

* `in’ is used with:

seasons:in autumn, in the spring
years and centuries:in 1985, in the year 2000, in the nineteenth century
months:in July, in December
parts of the day:in the morning, in the evenings

Note that you also use `in’ to say that something will happen during or after a period of time in the future.
I think we’ll find out in the next few days.

* `on’ is used with:

days:on Monday, on Tuesday morning, on Sunday evenings
special days:on Christmas Day, on my birthday, on his wedding anniversary
dates:on the twentieth of July, on June 21st

3 You use `for’ with verbs in any tense to say how long something continues to happen.
He is in Italy for a month.
I remained silent for a long time.
I will be in London for three months.

WARNING: You do not use `during’ to say how long something continues to happen. You cannot say `I went there during three weeks’.

4 You use `since’ with a verb in the present perfect or past perfect tense to say when something started to happen.
Marilyn has lived in Paris since 1984.
I had eaten nothing since breakfast.

5 You can use many other prepositional phrases as adverbials of time. You use:

* `during’ and `over’ for a period of time in which something happens
I saw him twice during the holidays.
Will you stay here over Christmas?

* `from…to/till/until’ and `between…and’ for the beginning and end of a period of time
The building is closed from April to May.
She worked from four o’clock till ten o’clock.
Can you take the test between now and June?

* `by’ when you mean `not later than’
By eleven o’clock, Brody was back in his office.
Can we get this finished by tomorrow?

* `before’ and `after’
I saw him before the match.
She left the house after ten o’clock.

`Since’, `till’, `until’, `after’, and `before’ can also be conjunctions with time clauses.
See Unit 96.

I’ve been wearing glasses since I was three.

6 You use the adverb `ago’ with the past simple to say how long before the time of speaking something happened. You always put `ago’ after the period of time.
We saw him about a month ago.
John’s wife died five years ago.

WARNING: You do not use `ago’ with the present perfect tense. You cannot say `We have gone to Spain two years ago’.