After reading the sentence and locating the infinitive phrase in it, we can underline the phrase in the following manner:
To plan a successful vacation takes a good deal of thought.
Infinitive phrases
Infinitive phrases are groups of words comprised of a verb in the infinitive form (to + base form of the verb) and modifiers or other words related to the infinitive. They can function in the sentence as:
In the sentence we are analyzing here, the infinitive phrase is "To plan a successful vacation." It functions as the subject of the sentence. The infinitive is "to plan".
Learn more about infinitive phrases here:
https://brainly.com/question/2478873
