Final answer:
The corrected sentence is 'Tomorrow's game has been postponed until next Wednesday,' using the apostrophe to show possession for 'tomorrow'.
Step-by-step explanation:
The correct sentence with the appropriate use of an apostrophe should be: 'Tomorrow's game has been postponed until next Wednesday.' In this sentence, 'Tomorrow's' is a contraction, which stands for 'Tomorrow is.'
The use of the apostrophe here indicates possession, implying that the game that belongs to or is associated with tomorrow has been postponed. The apostrophe is also used to show contractions where letters are omitted, and although that is not the case here, it's important to know both uses to avoid confusion.