Answer:
1. The correct answer in this question is friends'.
2. The correct answer in this question is boxes'.
3. The correct answer in this question is houses'.
4. The fourth question is already correct.
5. The correct answer in this question is people's.
Explanation:
The possessive in English is formed by adding an apostrophe and an "s" to the singular noun. When the noun is in plural, we would add only the apostrophe if the noun ends in an "s," or the apostrophe+"s" if the noun ends in a different letter. Possessives show relationships of belonging between one thing and another.
