Answer :
Answer:
See Explanation Below
Explanation:
Presupposition is what is assumed by a speaker to be the case before to making an utterance.
We can also say that, a presupposition constitutes a necessary assumption that is required to understand the meaning of a sentence.
As used in the example above, the prepositions explains that the minors were drinking when they were caught by the police before they promise not to do so again
So the presupposition of the given exercise are as follows;
a. We've been to the ballpark before
b. Valerie did not receive a new T-bird for Labor Day.