A conditional sentence is a complex sentence with a subordinate clause of condition that usually begins with the conjunction IF. The clause of condition (the if-clause) indicates the conditions under which the action in the main clause may be realized.
If only
This adds emphasis to hypothetical situations. With past events it adds a
sense of regret. The second part of the sentence is often left out.
If only I had enough time!
If only I hadn't drunk too much, this wouldn't have happened!
Happen to
This emphasises chance possibilities. It is often used with should.
If you happen to see Helen, could you ask her to call me?
If you should happen to be passing, drop in for a cup of tea.
Will and would: politeness and emphasis
These can be used as polite forms.
If you will/would wait here, I'll see if Mrs Green is free.
Will can also be used for emphasis, meaning 'insist on doing'.
If you will stay out late, no wonder you are tired! (insist on staying out)
• Supposing
Supposing or suppose can replace if, mainly in everyday speech.
Supposing you won the football pools, what would you do?
But for
This can replace if not. It is used in formal language, and must be followed
by a noun form.
If you hadn't helped us, we would have been in trouble.
But for your help, we would have been in trouble.
If and adjectives
In expressions such as if it is necessary/possible it is possible to omit the
verb be.
If interested, apply within.
If necessary, take a taxi.
