1. Don't throw away your old clothes, shoes, or books.

They will be useful to someone.
2. You can buy things at low prices.
3. Don't throw away your old clothes, your old shoes, or your old books.
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Q1: Are "your old clothes, shoes, or books" in generic use?
Or are they just mean some of "your old clothes, shoes, or books" or many of "your old clothes, shoes, or books"?
Q2: In #2, is the word 'things' in generic use? Or does things just mean some things?
Q3: Does #1 always mean #3?

Q1 - yes, "your clothes, shoes, or books" means all of them, not just a few or some of them.

Q2 - "things" means material goods generally, nothing specific (not some, but all).
Q3 - yes, one and three mean the same. Repeating "your" before each item in the series is not necessary, though. Number one is best.

A1: In the given sentences, the phrases "your old clothes, shoes, or books" are used in a generic sense. This means that they refer to any or all of your old clothes, shoes, or books, as opposed to just some specific ones.

A2: In sentence #2, the word "things" is used in a generic sense. It refers to any general items or objects that you can buy at low prices. It does not specify any particular items.

A3: Yes, sentence #1 and sentence #3 essentially convey the same message and have the same meaning. Both sentences emphasize the importance of not throwing away your old clothes, shoes, or books because they can still be useful to someone. The phrasing may differ slightly, but the intention and main idea remain the same.