Prepositions of time (A2)

In this lesson, you will review in, on, and at, and learn other common time expressions.

Quick revision: in / on / at

Remember the basics from A1:

• in: months, years, seasons, parts of the day (morning, afternoon, evening)
  Example: I was born in July.
• on: days, dates
  Example: My birthday is on Monday.
• at: exact times and the fixed expression at night
  Example: We eat dinner at 7 o'clock.

Now you will learn some more common time words and expressions.

More time expressions

By vs until / till

• By → not later than a certain time; it shows a deadline.
  Example: I have to finish my homework by 6 p.m. (= no later than 6 p.m.; maybe before 6, maybe exactly at 6).

Tip: “By” shows a deadline. It focuses on completion.

• Until / Till → an action continues up to a specific time and then stops.
  Example: She stayed at home until 7 o’clock. (She was at home the whole time up to 7 o’clock. At 7 o’clock, she left.)
  Example: They stayed at the party till midnight. (They stayed until midnight.)

Compare: by 7 o’clock = before or at 7; until 7 o’clock = continuing up to 7.

For vs since

• For → shows duration, how long something lasts.
  Example: I have lived in London for three years. (Duration: three years.)
  Example: We have been waiting for 30 minutes. (Duration.)
• Since → shows the starting point of an action or situation.
  Example: She has been studying English since 2020. (Starting point: 2020.)

We often use since with the present perfect: I have lived here since 2020. This means I started living here in 2020 and I still live here now.

During vs for

• During → something happens within a period of time.
  Example: She fell asleep during the lesson. (At some point in the lesson.)

Use during with a noun: during the lesson, during the summer.

• For → something lasts for a length of time.
  Example: I slept for two hours.

Use for with a length of time: for two hours, for three weeks.

Compare: I slept during the lesson. (= inside that time period.) / I slept for two hours. (= duration, how long.)

Do not say: during two hours; say for two hours.

Other useful time expressions

Before

• Before → earlier than another event or time.
  Example: They arrived before the meeting started. (Earlier than the meeting.)

Ago

• Ago → used after a time period to show how long before now something happened. Pattern: [time period] + ago.
  Example: He left the office two hours ago. (Two hours before now.)
  Example: I saw her three days ago. (Three days before now.)

Later / Afterwards

• Later means at a later time.
  Example: I’ll call you later.
• Afterwards means after an event that you have already mentioned.
  Example: We had dinner and afterwards watched a film.

Recap

• in → long periods: months, years, seasons, parts of the day
• on → specific days or dates
• at → exact times and the fixed expression at night
• by → deadline (finish before this time)
• until / till → continue up to a time, then stop
• ago → time before now (past)
• during → within a period of time
• for → duration (how long)
• since → starting point
• before → earlier than an event or time
• Later / afterwards → after another time or event

Choose the expression by asking: Is it a day/date, an exact time, a duration, a starting point, a deadline, a period/event, time before now, or time earlier/later than another event?