Unless is similar in meaning to if not and can be used instead of if not in certain types of conditional sentences. We normally use unless with present tenses when we are referring to the future:
- You won’t get in to see the show, if you don’t have reserved seats. OR: Unless you have reserved seats, you won’t get in to see the show.
- Let’s play tennis on Saturday, if it’s not raining. OR: Let’s play tennis on Saturday, unless it’s raining.
- I’ll see you at the gym this evening, if you’re not too tired. OR: I’ll see you at the gym this evening, unless you’re too tired.
Don’t use ‘unless’ in questions
- What will you do if you don’t pass those exams? If I don’t pass those exams, I won’t be able to study in Australia.
Don’t use ‘unless’ with would to talk about unreal future situations
- If he didn’t take everything so seriously, he would be much easier to work with. If he weren’t so bad-tempered, I would help him to get the work done
Don’t use ‘unless’ with would have to talk about unreal situations in the past either
- If you hadn’t driven so recklessly, you wouldn’t have had this accident. If you hadn’t had that last glass of wine, this would never have happened.
Use ‘unless’, and not if not, if we are introducing an idea as an afterthought
- I won’t bother going to the meeting at the school tonight – unless you want to go, of course.
unless + past participle
Unless can be used with a past participle in a reduced clause when you choose to leave out the subject words and the auxiliary verbs in the brackets in the examples below:
- Don’t shut down these computers unless (you are) instructed to do so. Just log off. Unless (he is) given sufficient warning of the consequences, he will continue to misbehave.
However, this sounds quite formal and in spoken English we would normally keep subject words and auxiliary verbs.
Answering negative questions
When a yes/no question is asked with a negative, it can be difficult to know what the correct way to respond is.
Think of a negative question as if it were a positive question and answer it like that!
Aren’t you going out tonight? is the same as: Are you going out tonight? For both questions the answer will be the same.
Yes, I am = you are going out tonight.
No, I’m not = you are not going out.