- Take an umbrella in case it rains. (= . . . because it might rain.)
I’ve bought a chicken in case your mother stays to lunch.
I wrote down her address in case I forgot it.
After in case, we use a present tense with a future meaning.
- . . . in case it rains. (NOT . . . in case-it-will rain.)
We can also use should + infinitive. In this structure, should means ‘might’.
- I’ve bought a chicken in case your mother should stay to lunch.
I wrote down her address in case I should forget it.
The structure with should is more common in the past.
- ‘I do A in case B happens’ =
‘I do A first because B might happen later.’ A is first.
‘I do A if B happens’ =
‘I do A if B has happened first.’ B is first.
- Let’s get a bottle of wine in case Roger comes.
(= We’ll buy some wine now because Roger might come later.)
Let’s buy a bottle of wine if Roger comes.
(= We’ll wait and see. If Roger comes, then we’ll buy the wine. If he doesn’t we won’t.).