In the sentence Although book was more than 50 years old it still contained helpful information word Is although a verb preposition adjective or conjunction?

In the sentence "Although the book was more than 50 years old, it still contained helpful information", the word "although" is a conjunction.

Here's why:

* Conjunctions connect words, phrases, or clauses.

* "Although" introduces a subordinate clause ("the book was more than 50 years old") that provides a contrast to the main clause ("it still contained helpful information").

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