Final answer:
Fill the blank with 'had already' to accurately convey that Louise informed her father of her plans to go to the park before she went, using the past perfect tense.
Step-by-step explanation:
In the sentence "Louise ______ told her dad she was going to the park, so he wasn't surprised when she went," the correct word to fill in the blank is "had already." This phrase indicates that Louise previously informed her father of her plans, which is why he was not surprised by her action. The word choice here helps to convey the idea that the action of telling her father occurred before the action of going to the park, and using the past perfect tense 'had already' succinctly demonstrates the sequence of events.
Consider the role of verb tense in English grammar when constructing sentences to depict the chronology of two events happening one after the other. Here, Louise's informing her father (prior event) and her going to the park (subsequent event) are connected in a way that one event is not a surprise due to the completion of the other event.
Using specific tenses, such as the past perfect tense, allows the writer to be clear about the order in which the events occurred and the causal relationships between them. In this case, the correct verb tense gives clarity to the storyline and to understanding Louise's interaction with her father.