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You are here: Level A2 > When,As soon as,Until,By,Once

Prepositions of time: when, as soon as, until, by, once


  • asking about time (When do you come home from work?)

  • one action follows the other (I'll do it when I get home.). It doesn't say that one action follows the other immediately.


We use present simple tense after 'when' but the meaning is for the future:

When I come home tomorrow, I'll cook dinner for you.

Will you call me when you get that parcel, please?

When they build the house next year, we'll move in.

As soon as

  • we use it to say one action happens right after another

  • immediately after another

We use present simple tense after 'as soon as' but the meaning is for the future:

Call me as soon as you arrive home. (immediately after you get home!)

I will make me a coffee as soon as I arrive at work (the first thing I'll do at work in)

I'll open the parcel as soon as I get home.

Until, till (till is informal)

  • a situation continues up to a certain moment:

    They worked from 9 till 5 yesterday.

    We didn't come home until very late on Friday night.

  • is often used with negative verbs:

    He didn't do it until the boss told him.

    We didn't leave the house until my parents arrived.

We use present simple tense after 'until/till' for the future:

I won't open it until you come back.

We won't go until you give us some money.


    • an action happens at/before a certain moment in future

    • the latest possible time when an action happens

      They'll repair my car by next Tuesday. (it will be done before next Tuesday)

      I'll finish this book by summer. (it can be earlier than that)

      Send me your report by tomorrow. (tomorrow is the deadline)


    • after, as soon as

    • at once: immediately

    • it is often used with perfect tenses

    Once you've passed the test, you can drive my car.

    Once he had come home, he called his mum.

    I'll do it at once (immediately).