English Grammar Course Unit 9: When and If sentences (When I do…/If I do…)

Why should you study this unit?

In the last few units, we talked about using will and going to to talk about future events. Let’s now move on to discuss about the possibility of those future events. When we refer to a future event, we cannot be certain whether the event will take place or not. Right? So how would you talk about these two situations for instance? let’s say you want to shop for new clothes for a festival, but you are not sure when or you don’t know how long you will be in a meeting but you have tell your friend not to wait for you.

This unit will tell you how.

English Grammar Course When and If sentences

A. Study this example :

  • What time will you call me tonight?
  • I’ll call you when I get home from work.

“I’ll call you when I get home from work” is a sentence with two parts:

“I’ll call you” (the main part) and “when I get home from work” (the when part). The sentence is future (tonight), but you cannot use will or going to in the when part of the sentence. Instead we use a present tense, usually simple present (I do).

  • I can’t talk to you now. I’ll talk to you later when I have more time. (Not
    when I’ll have)
  • When the rain stops, we’ll go out. (Not when the rain will stop)

The same thing happens after: while, after, before, until/till, as soon as.

  • Can you take care of the children while I am out? (Not will be)
  • Before you leave, you must visit the museum. (Not will leave)
  • Wait here until I come  (Not will come)

B. You can also use the present perfect (I have done) after when/after/until, etc., to show that the first action will be finished before the second:

  • After I’ve read this book, you can have it.
  • Don’t say anything while Tom is here. Wait until he has gone.

It is often possible to use either the simple present or the present perfect:

  • I’ll come as soon as I finish or I’ll come as soon as I’ve finished.
  • You’ll feel better when you have or you’ll feel better when you’ve had
    something to eat.

C. After if we also use the simple present (I do) for the future:

  • It’s raining. We’ll get wet if we go  (Not if we will go)
  • Hurry up! If we don’t hurry, we’ll be late. (Not if we won’t hurry)

Be careful not to confuse when and if.

Use when for things those are sure to happen:

  • I’m going shopping this afternoon.When I go shopping, I’ll buy some food.

Use if (not when) for things that will possibly happen:

  • I might go shopping this afternoon.If I go shopping, I’ll buy some food.
  • If it rains this evening, I won’t go out. (Not when it rains)
  • Don’t worry if I’m late tonight. (Not when I’m late)
  • If he doesn’t come soon, I’m not going to wait. (not when he doesn’t come)

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