Say when and how often it will happen

In A2 #27 you learnt the rule for conditional sentences: after if about the future you use the present tense — If it rains, I'll stay at home, not ✗ If it will rain. The future is already named in the main part (I'll stay), and the part with if only says under what condition it will happen.

Conjunctions of time work in exactly the same way. The part with when, as soon as, until, before, after, by the time says at what moment something will happen, and there is no future tense in it, although many languages put one there: I'll call you when I get there — not ✗ when I will get there. One will is enough for English in the whole sentence: the main part has already said that we are talking about the future.

The form. In the main part — will, going to, the imperative or a modal verb. In the part with the conjunction — the Present Simple.

till is the conversational variant of until and means the same. After while there is usually the Present Continuous: while talks about a process that is going on — and that is a present tense too.

Negatives and questions are built by the usual rules, and the tenses are the same: the future in the main part, the present after the conjunction. I won't leave until you get back. What will you do when you finish university? Will you call me as soon as you hear something?

The order of the parts is free. If the part with the conjunction comes first, it is followed by a comma: When I get home, I'll call you. If it comes second, there is no comma: I'll call you when I get home. This is the same rule as in a story about the past (B1 #2).

"When I've finished" — the Present Perfect. If it matters that one job will be completely done before another one starts, the Present Perfect goes after the conjunction: I'll send you the report when I've finished it. — I'll send it when the whole report is done. As soon as I've read the book, I'll give it back. People say this most often after when, after, as soon as, once, until. The Present Simple is also correct here; the Present Perfect stresses that the job will be done. There is no future tense here either.

When it is used. Three typical situations:

• to arrange something and promise: I'll text you as soon as I land. — the message will come right after the plane lands;
• to give an instruction: Don't open the door until the light goes green. — keep it closed, and open it when the light is green;
• to plan step by step: After we've had lunch, we'll go to the museum.

until — with no "not". In some languages the word for until comes with a "not", although the meaning is positive: Italian aspetta finché non torno, Polish poczekaj, dopóki nie wrócę — "wait until I come back". In English until itself means "up to the moment that", and there is no second negative after it: Wait until I come back. If the negative is in the main part, the meaning is "not before": I won't pay until I see the car. — first I see the car, only then do I pay.

Compare with if and with a question. when has two neighbours, and it is confused with both:

The check is simple. If you ask "when?" or say that you don't know when, it is a question, and will stands in it as in any question about the future. If when names the moment at which the main action will happen, it is a conjunction, and after it comes the present.

How often: every. every + a singular noun names a regular repetition: every day, every Monday, every summer. With a number you get an interval: every two weeks — once in two weeks, every three hours — with three hours between the times. The noun is plural here, because every refers to the whole group "two weeks". every other day is every second day: one day yes, the next day no. Together with once a week, twice a month (A1) these are two ways to talk about frequency: once a week — how many times in a period, every two weeks — how long the gap between the times is.

every time and whenever — "each time that". These are conjunctions of time too, and the rule for them is the same: about the future, the present goes after them. Every time I see him, he's on the phone. — about what always happens. Whenever you're in Leeds, come and see us. — about the future, but you're, not ✗ you'll be.

every and each. Both mean "all the people or things, one by one", both stand before a singular noun, and the verb after them is singular too: Every room has a TV. Each room has a TV. The difference is in how the speaker looks at the group:

They also differ in form:

• each can be about two: She had a bag in each hand. every is only about three or more.
• each can stand on its own and with of: each of us, each of the rooms, We each got a copy. every can't do this: ✗ every of us → ✓ each of us or every one of us.
• With almost, nearly, not only every works: almost every day, Not every hotel has a lift.

Where both are possible, the difference is hardly noticeable: every time and each time mean the same.

More examples:

Don't say this. ✗ every days → ✓ every day. After every without a number the noun is always singular.

Check yourself. A friend is travelling to see you. You want a phone call from them the moment they arrive. What do you say? Why is there will in I don't know when she'll arrive? each or every: She wore a ring on ___ hand?