Final answer:
The three key words that signal a summary or conclusion are 'Ultimately', 'Basically', and 'In conclusion'.
Step-by-step explanation:
The three key words which signal a summary or conclusion are: Ultimately, Basically, and In conclusion.
These words are commonly used to signal that the speaker or writer is wrapping up their thoughts and summarizing the main points. For example, someone might say, 'Ultimately, the party was a success because everyone had a great time, there was plenty of food and entertainment, and we received positive feedback from the guests.'
Another example is, 'Basically, the experiment proved that plants grow faster with sunlight and water compared to being kept in the dark.'
And finally, 'In conclusion, the main characters in the story learned important lessons about friendship and standing up for what is right.'