Page 273 - Practical English Usage 3ed - Michael Swan, Oxford

264 if I were you 1 advice
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We often use the structure If I were you . .. to give advice. I shouldn't worry if I were you.
If I were you, I'd get that car serviced.
If I was you is also possible. Some people consider it incorrect (see 258.4). I shouldlwould ...
Sometimes we leave out IfI were you, and just use I should . .. or I would . .. to give advice.
I shouldn't worry. I would get that car serviced.
In this case, I should/would is similar to you should/would.
if only
We can use If only . ..! to say that we would like things to be different. It means the same as I wislt ... (see 630), but is more emphatic. The clause with ifonly often stands alone, without a main clause. Tense use is as follows:
a past to talk about the present
If only I knew more people! If only I was better-looking! We can use were instead of was (see 258.4).
If only your father were here!
b would + infinitive (without to) to talk about the future If only it would stop raining, we could go out.
If only somebody would smile!
c past perfect to talk about the past
If ollly she hadn't told the police, everything would have been all right.
ill and sick
III and sick are both used to mean 'unwell'. (In American English ill is less usual except in a formal style.)
George didn't come in last week because he was iWsick. III is not very common before a noun.
I'm looking after my sick mother. (More normal than ... my ill mother.) Be sick can meant 'vomit' (= bring food up from the stomach).
I was sick three times in the night.
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