To find a quotation you would use Bartlett's corpus of quotations including over 1100 quotations. Webster is a dictionary maker while Roget made thesauruses.
Explanation:
problem and solution essay-->Sara studied the reason for discarding the painting at that time.
descriptive -->Finding the watering hole was the most important part of the expedition studying the animal’s habitat.
cause ------>The team decided to challenge the call so that they might still be able to make the playoffs.
compare -->There is an assumption that democracy is failing in eastern Europe. On the contrary, it is far healthier there than in parts of western Europe.
Citing passages from a text is one way to provide elaboration in an essay.
The reason why this would be your answer is because when you cite your source, it allows to person to go to the source to see more information about the quote you got, and not leave them empty handed. If you didn't cite you source, it would be considered plagiarism, and wouldn't allow the reader to get to know more about the quote and what happens.
Introduction.
A book's introduction is closely related to the content of the book itself. Usually found in nonfiction work, the introduction may summarize the main argument presented in the rest of the book, define any important terms, or fill in background details.