- For Teachers
6. Other expression with IF
ONLY IF: Teachers may detain students after school only if they have given parents 24 hours’ notice in writing of the detention
Only if stresses the exclusivity of the condition - if the condition is not fulfilled, the situation in the main clause is expressly excluded. Omission of only merely implies the exclusion
IF ONLY: If only I had known that Jill had had cancer [I wouldn’t joked about her appearance].
If only makes hypothetical and counterfactual conditionals expressing surprise or regret stronger. The main clause consequence is often omitted, its message being implied.
EVEN IF: Even if Pompey win all their remaining matches, they can’t escape relegation.
Even if is used when the condition has no effect on the subsequent clause; in  the relegation will occur whether or not Pompey win all their remaining matches.
Certain warnings/threats with and and not ….or convey a message very similar in meaning to conditional utterances, though they are not conditional constructions: The first of the following is a conditional warning; the other two are not.
If you come home so late home again, I’ll ground you for a month.
Come home so late home again and I’ll ground you for a month.
Don’t come home so late home again or I’ll ground you for a month.
Copyright © 2012 Jed Webb
Written by JE Webb for UsingEnglish.com
About the author:I began teaching in 1967, and, apart from post-grad studies, have been teaching and writing ever since. I've taught French and Herman in British secondary schools and FE Colleges, and EFL at schools and universities in China, the Czech Republic, Estonia.,