Conditional Sentences: Conditional Sentences (#9)

In addition to the "normal" forms of conditional sentences
("if" sentences showing a condition and a result), you will
sometimes see a "shortened" type of conditional construction
in formal writing. This kind of "abbreviated" conditional is
most commonly seen in past unreal situations:

If we had known about the meeting,
we would have attended. --->

Had we known about the meeting,
we would have attended.

If he had been here, he could have
helped us. --->

Had he been here, he could have
helped us.

If she hadn't applied early, she wouldn't
have been accepted. --->

Had she not applied early, she wouldn't
have been accepted.

If you hadn't left an hour early, you would
have been late for the meeting. --->

Had you not left an hour early, 
you would have been late for the meeting.

This same pattern is also seen in present / future unreal
conditional sentences that use should:

If I should see him, I'll give him
the message. --->

Should I see him, I'll give him
the message.

If you should need anything,
please call me. --->

Should you need anything,
please call me.

If he should call you,
I also want to speak to him. --->

Should he call you,
I also want to speak to him.

Special Note:

Except with should, this pattern is not normally used with
present / future unreal conditionals.