
Apostrophes are used in time expressions; also known as temporal expressions.
In a temporal expression an apostrophe is positioned before the ‘s’ for a singular unit of time and after the ‘s’ for more than one.
E.g. I never did a day’s work in my life.
That is the equivalent of one year’s pay.
Please note it’s not always about time! Most of the expressions are time related but some relate to value and distance.
E.g. 5 euros’ worth of onions and 1 euro’s worth of potatoes.
One good tip to remember – Only use an apostrophe in an expression where the word ‘of’ might have been used. E.g. six months’ insurance.