When reporting a zero conditional, the following tenseA grammatical category that is marked by verb inflection. To express when an event or action happens in time or when a state exists, we use tenses. changes may be applied.

The rules that apply here are essentially the same as those discussed on the previous pages, that is, tenseA grammatical category that is marked by verb inflection. To express when an event or action happens in time or when a state exists, we use tenses. and modal changes occur if the reported sentence is out of date at the timeA concept which is related to our perception of reality; that part of existence which is measured in seconds, minutes, hours, days, weeks, etc. of reporting. Note that, even in this case, some tenses and modals do not change.

My leg's broken. I can't stand up unless you help me.

Unless means if not, therefore negation is not possible after it:

I can't stand up unless you don't help me.

The meaning of these connectors is similar to that of provided or if. They are used in informalBelonging to colloquial or everyday speech E.g.: I want Mr Smith to call the guy that the committee has decided on. or everyday language.

Suppose/supposing you won the lottery, what would you do?

Provided/providing and as long as can replace if in conditional sentences. These are usually used in the first conditional, and sound a bit formalNot belonging to colloquial or everyday speech; official. E.g.: I demand that Mr Smith call the person on whom the committee has decided..

You can stay here as long as you keep quiet.
Provided/Providing (that) the bills are paid, tenants will not be evicted.

Only if can be used to connect the main clauseA group of related words containing a subject and a verb. and the if-clause to express a more restrictive condition.

Acetaminophen is dangerous to kids only if dosage is too high.

It is possible in all types of conditionals. Note that if the sentence starts with the condition, the main clauseA clause that could be a sentence in itself. E.g.: I wouldn’t go there if I were you. ("I wouldn't go there") When I arrived he was surfing. ("he was surfing") is invertA structure in which a verb or an auxiliary precedes the subject. E.g.: "Here comes the sun."ed.

Even if emphasisSpecial importance or attention given to something. E.g.: All I wanna do is have some fun.es that something will happen whatever the condition is. It is possible in all types of conditionals.

I will wear my red shirt even if you don’t like the idea.

In the if-clauseA group of related words containing a subject and a verb. of the first conditional we can use should (to express that the condition is less likely), can (permission or ability), will or would (willingness, insistence and refusal), must (obligation) or may (permission).

Instead of will here we can use may/might (certainty/uncertainty), may (permission), can (permission or ability) or must/should (obligation).

In this type of mixed conditional the if-clauseA group of related words containing a subject and a verb. is in the second, while the main clauseA clause that could be a sentence in itself. E.g.: I wouldn’t go there if I were you. ("I wouldn't go there") When I arrived he was surfing. ("he was surfing") is in the third conditional.

If Mr Douglas had a moustache, Ms Zeta Jones would probably not have married him.
If I were smarter, I would have been able to answer.

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